Epigenetic clocks provide clues to the mystery of uterine ageing

Mediation role of telomere length in the relationship between physical activity and PhenoAge: A population-based study

Background

The relationship between physical activity (PA), telomere length, and phenotypic age (PhenoAge) represents a pivotal area of investigation in aging research.

Methods

The study encompassed a cohort of 6200 participants aged 20 years and above, sourced from the National Health and Nutrition Examination Survey (NHANES). Physical activity (PA) levels were assessed employing the Global Physical Activity Questionnaire, while DNA samples were collected to determine telomere length, measured in base pairs. PhenoAge, an emerging aging index relying on nine distinct chemical biomarkers, was computed.

Results

Incorporating a fully adjusted model, our analysis showed significant correlations between PA engagement and PhenoAge [Low PA, β (95 % CI): 0.039(-0.071,-0.008), p = 0.021; Moderate PA, β (95 % CI): 0.058(-0.082,-0.034), p < 0.001; High PA, β (95 % CI): 0.069(-0.096,-0.042), p < 0.001]. Furthermore, a positive link emerged between elevated PA levels and telomere length, with a β (95 % CI) of 0.011(0.001, 0.022), p = 0.034. A mediation analysis was performed, demonstrating that telomere length mediated the connection between PA and PhenoAge, with a proportion mediated calculated at 3.57 %.

Conclusions

Our findings suggest that PA may play a key role in mitigating aging processes by preserving telomere length, highlighting the potential of PA as a target for interventions aimed at promoting healthy aging and longevity.

Mechanosensitive Piezo1 channel is highly expressed in the age-induced fibrotic uterus

BACKGROUND

As the trend of delayed childbearing continues, uterine aging is increasingly recognized as a critical factor impacting reproductive health and contributing to infertility. However, the underlying mechanisms of uterine aging remain poorly understood.

OBJECTIVE

This study aims to explore age-related changes in the extracellular matrix (ECM) and the involvement of Piezo1, a mechanically sensitive non-selective cation channel, in mediating Wnt/β-catenin signaling within the aging uterus of rats.

METHOD

Eighteen female rats were divided into three age groups: 3 months (n = 9), 9 months (n = 9), and 18 months (n = 9). We performed comparative analyses of Piezo1 expression and fibrosis-related gene expression through immunohistochemical staining. Morphological changes in the uterine tissue were observed using Hematoxylin and Eosin (H&E) and Masson staining techniques.

RESULTS

Our findings revealed significant morphological and molecular alterations in the uterine tissue of aging rats. The endometrium became thinner, glandular structures decreased, and fibrotic deposits were evident with advancing age. Additionally, aging was associated with reduced endometrial cell proliferation. ECM-related genes, including PAI, CTGF, Fn, α-SMA, TGFβR, MMP9, MMP13, and CDH1, were upregulated in the 18-month-old group compared to the 3-month-old group. Furthermore, an increased abundance of Piezo1 protein and activation of the Wnt/β-catenin signaling pathway were observed in fibrotic uterine tissues of aged rats.

CONCLUSION

In conclusion, our study identifies uterine fibrosis as a key feature of age-related changes in the rat uterus, with Piezo1 highly expressed in fibrotic uterus and may potentially playing a crucial role in this process by activating the Wnt/β-catenin pathway. These findings provide new insights into the molecular mechanisms of uterine aging, with potential implications for addressing age-related infertility.

Psychological stress on cancer progression and immunosenescence

Diagnosis and treatment of cancer constitute a deeply stressful experience that involves unique and common problems and generates uncertainty, fear and emotional distress. Furthermore, there are reciprocal interactions between psychological stress and cancer in the clinical settings. Therefore, it is crucial to understand the links of stress with cancer. A growing body of epidemiological and preclinical studies have suggested that stress affects cancer progression, and metastasis and treatment outcomes. Furthermore, stress elicits premature aging and deterioration of the immune system (known as immunosenescence), causing vulnerability to infections, autoimmune diseases, and cancers. In this review, we describe recent advances in how stress affects cancer progression through specific stress hormones and receptor systems as well as intracellular molecular processes, and discuss how stress-evoked neuroendocrine molecules regulate local and systemic immune responses in the tumor microenvironment. Furthermore, we review the molecular mechanisms of immunosenescence and evidence of psychological stress-evoked immunosenescence, highlighting the clinical value for available psychological and/or pharmacological interventions for psychological stress in patients with cancer. Based on existing evidence and emerging mechanistic insights, factors linked with psychological stress, immunosenescence and complications in cancer survivors need to be determined in future studies, and screening programs should be added to follow-up.

Polycystic Ovarian Syndrome: A Review of Multi-omics Analyses

Polycystic Ovary Syndrome (PCOS) is among the most prevalent endocrinological abnormalities of young females, posing a grave public health challenge to the society. The objective of the present literature review is to analyze the enormous amount of information available by way of numerous multi-omic studies, and to explore a meaningful relationship between various factors such as genetic, proteomic, environmental etc. to understand the multifactorial metabolic disorder in a proper manner. Detailed literature search was done in various science article repositories and biomedical databases such as PubMed, Google Scholar, BioMed Central, Embase etc. by using several keywords in whole gamut of combinations. PCOS is a heritable disease. It manifests as a result of a combination of several intricately inter-linked symptoms such as anovulation, obesity, type II diabetes, hyperandrogenism, polycystic ovaries etc., the last one being the main manifestation of the disease, thus leading to infertility among several other complications. Such a multifactorial metabolic disorder with extreme symptomatic heterogeneity cannot be fully explained solely based on symptoms or genetic variations; thus, giving some space of thought to other factors such as epigenetic, microbiomic factors etc. playing a role in the causation of the disease. The present scientific survey of literature extensively reviews various aspects of PCOS by critically looking into the vast multi-omic data, and concluded with suggesting treatment options as well as lifestyle changes required to deal with the psychological/ emotional impacts of the condition on affected women.

Causes of embryo implantation failure: A systematic review and metaanalysis of procedures to increase embryo implantation potential

Introduction

Infertility is characterized by the failure to conceive after 12 months of unprotected sexual intercourse. In assisted reproduction technologies (ARTs), in-vitro fertilization and embryo transfer (IVF-ET) are pivotal, with the quality of embryo quality essential for successful implantation.

Objective

This systematic review with meta-analysis aimed to explore the prevalence of embryonic factors involved in the implantation process, concentrating on the following research inquiries: 1) the implantation rates of euploid versus untested embryo transfers; 2) the efficiency of transferring good embryos in different age groups; 3) the impact of age on good embryo transfers to gestational carriers; and 4) the transfer of donated gametes/embryos. The goal is to identify critical points in implantation to improve therapies.

Methods

A comprehensive literature search identified 1474 relevant papers, 11 of which met the inclusion criteria. The information was gathered using a standardized form, and the risk of bias was evaluated. A meta-analysis of subgroups to determine euploid embryo transfer efficiency was conducted to synthesize and explore the results. Furthermore, data extracted from registries document the persistent secondary role of extraembryonic determinants in successful implantation.

Results

The meta-analysis demonstrated that preimplantation genetic testing for aneuploidy (PGT-A) significantly increased the odds of implantation. Age was found to influence extraembryonic factors, with older women experiencing reduced embryo implantation as gestational carriers. However, the overall incidence of extraembryonic factors was low. This review highlights the need to focus on PGT-A, diagnostic hysteroscopy, and endometrial receptivity for improving implantation rates.

Conclusion

Implantation success in ARTs largely depends on embryo euploidy. While achieving three euploid embryos greatly increases success rates, it is challenging in older women. Extraembryonic factors, although present, have a marginal impact. Subsequent studies ought to concentrate on modulating endometrial responses immunologically and developing algorithms to improve the precision of predicting implantation success; as well as the timing of endometrial receptivity and the occurrence of dormant embryo phenomena also warrants further investigation.

Role of epigenetic regulation in diminished ovarian reserve

Diminished ovarian reserve (DOR) is characterized by a decrease in the number and quality of oocytes, with its incidence increasing annually. Its pathogenesis remains unclear, making it one of the most challenging problems in the field of assisted reproduction. Epigenetic modification, a molecular mechanism affecting genomic activity and expression without altering the DNA sequence, has been widely studied in reproductive medicine and has attracted considerable attention regarding DOR. This review comprehensively examines the various epigenetic regulatory changes in ovarian granulosa cells (OGCs) and oocytes during DOR. DNA methylation plays a crucial role in regulating granulosa cell function, hormone production, and oocyte development, maturation, and senescence. Histone modifications are involved in regulating follicular activation, while non-coding RNAs, such as long noncoding RNAs (lncRNAs) and microRNAs (miRNAs), regulate granulosa cell function and oocyte development. N6-methyladenosine (m6A) modifications are associated with age-related oocyte senescence. Epigenetic clocks based on DNA methylation show potential in predicting ovarian reserve in DOR. Furthermore, it discusses the potential for utilizing epigenetic mechanisms to better diagnose and manage DOR.

Equol Alleviates the In Vitro Aging-Induced Disruption of Porcine Oocytes

Oocyte quality is crucial for determining the subsequent embryo developmental capacity and reproductive outcomes. However, aging is detrimental to oocyte quality. Previous studies have demonstrated that soy isoflavones have positive effects on the reproductive performance of female pigs. Equol, the primary metabolite of soy isoflavones, is renowned for its antioxidant properties and its ability to scavenge reactive oxygen species (ROS). However, the potential role of equol in reversing aging-mediated oocyte decline has not yet been elucidated. In this study, we treated the porcine oocytes with different concentrations of equol (2.5, 5 and 10 μM) during prolonged in vitro culture. Our findings showed that aging led to decreased embryonic developmental capacity, indicating the decline of oocyte quality. We further found that aging disrupted spindle assembly and chromosome arrangement, impaired actin polymerisation and reduced mitochondrial activity and function. Moreover, aging increased ROS levels; thereafter, DNA damage and apoptosis was induced in the porcine oocytes. Interestingly, treatment with 2.5 μM equol during the aging process significantly mitigated the above-mentioned defective parameters in porcine oocytes and finally improved embryo development rates. Collectively, these results imply that equol has potential benefits in attenuating the aging-mediated defects on porcine oocytes.

Bushen Jianpi Tiaoxue Decoction (BJTD) ameliorates oxidative stress and apoptosis induced by uterus ageing through activation of the SIRT1/NRF2 pathway

BACKGROUND

Uterus ageing is a crucial factor contributing to decreased fertility in older women and is also implicated in menstrual disorders, endometritis, and adenomyosis. Bushen Jianpi Tiaoxue Decoction (BJTD) is a traditional Chinese medicine formulation used to ameliorate endocrine disorders in the female reproductive system and finds extensive application in ageing-related endometrial diseases. However, the mechanisms underlying its improvement of uterus ageing have not been thoroughly investigated.

PURPOSE

To explore the potential components and mechanisms of BJTD in ameliorating uterus ageing through network pharmacology, in vivo, and in vitro experiments.

METHODS

Morphological changes were observed using hematoxylin and eosin staining, collagen deposition was assessed using Masson staining, and apoptotic-related molecules were detected using Western blot. After determining the modeling doses, BJTD intervention was administered at two doses, and the expression of oxidative stress and apoptosis-related genes and proteins was measured. The levels of cellular apoptosis were evaluated using the TUNEL assay kit and Annexin V/FITC-PI assay kit. The main components of BJTD were determined by UPLC-MS, and the potential targets and mechanisms of BJTD action were explored using network pharmacology and molecular docking. BJTD-Containing Serum (BJTD-S) was extracted and applied in vitro experiments using human endometrial stroma cells (hESC) to preliminarily identify the pathways affected.

RESULTS

We demonstrated that modeling with 600 mg/kg/day D-Gal for 5 weeks significantly increased collagen deposition in uterine tissues, particularly in the glands and stroma. Additionally, it significantly elevated the levels of TNF-α and IL-1β and increased the expression of p53 and BAX while decreasing BCL-2 expression. BJTD significantly reduced the increased levels of TNF-α and IL-1β induced by D-Gal, and modulated oxidative stress markers such as SOD, MDA, GSH-Px, and T-AOC. BJTD also inhibited the cascade activation of apoptosis induced by D-Gal, suppressing the expression of cleaved-Caspase 8, cleaved-Caspase 3, and BAX. SIRT1 is a potential target of BJTD action. In vitro experiments showed that BJTD-S significantly improved D-Gal-induced apoptosis in hESC cells, and the expression levels of SIRT1, NRF2, and HO-1 were significantly decreased in D-Gal-induced hESC, and BJTD-S significantly increased their expression.

CONCLUSION

BJTD can ameliorate oxidative stress and cell apoptosis levels in D-Gal-induced uterine aging, and its active ingredients can activate the SIRT1/NRF2 pathway to exert its effects. Importantly, our study provides novel insights into the molecular mechanisms by which traditional Chinese medicine influence uterus ageing. By specifically targeting the SIRT1/NRF2 pathway, BJTD presents a unique therapeutic approach that has not been extensively explored in previous studies, marking a significant advancement in the treatment of uterus ageing.

Epigenetic Clocks: Beyond Biological Age, Using the Past to Predict the Present and Future

Predicting health trajectories and accurately measuring aging processes across the human lifespan remain profound scientific challenges. Assessing the effectiveness and impact of interventions targeting aging is even more elusive, largely due to the intricate, multidimensional nature of aging-a process that defies simple quantification. Traditional biomarkers offer only partial perspectives, capturing limited aspects of the aging landscape. Yet, over the past decade, groundbreaking advancements have emerged. Epigenetic clocks, derived from DNA methylation patterns, have established themselves as powerful aging biomarkers, capable of estimating biological age and assessing aging rates across diverse tissues with remarkable precision. These clocks provide predictive insights into mortality and age-related disease risks, effectively distinguishing biological age from chronological age and illuminating enduring questions in gerontology. Despite significant progress in epigenetic clock development, substantial challenges remain, underscoring the need for continued investigation to fully unlock their potential in the science of aging.

TET1 overexpression affects cell proliferation and apoptosis in aging ovaries

PURPOSE

Along with the progress of society, human life expectancy has been increasing, and late marriage and late childbearing are the current trend. Since reproductive aging affects fertility, ovarian aging in women has become a major reproductive health issue in the current society. During ovarian aging, DNA methylation levels may change. The ten-eleven translocation (TET) protein family proteins TET1, TET2, and TET3 are important DNA demethylation enzymes, and differential expression of TET1, TET2, and TET3 may affect the proliferation and apoptosis of aging ovarian cells. The aim of this study was to investigate the role of TET1 in the regulation of ovarian aging.

METHODS

The expression of 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) was analyzed by immunofluorescence (IF) in young and aging ovaries of six 6-8-week-old female mice and six 6-8-month-old female mice. Then, the expression pattern of the TET protein family in young and aging ovaries of mice was investigated. To determine the impact of TET1 on ovarian development, the aging of IOSE-80, KGN, and SKOV-3 cells was induced with D-galactosidase (D-gal). Cells were then transfected using the TET1 overexpression vector or si-TET1. We assessed the proliferation and apoptosis of aging cells after transfection and analyzed the regulatory effect of TET1 expression on aging cells. Additionally, we verified the Tet1 expression in Tet1-KO mice.

RESULTS

The 5mC to 5hmC transition, oocyte maturation, and blastocyst rate were reduced in aging mice compared to young mice. In aging mice ovaries, the expression levels of Tet1, Tet2, and Tet3 were reduced significantly, with Tet1 being particularly pronounced. The overexpression of TET1 promoted proliferation and inhibited apoptosis in aging human ovarian cells. Furthermore, Tet1 expression was very low in Tet1-KO C57BL/6 J mice ovaries.

CONCLUSION

This study demonstrates that the expression levels of TET family proteins are low in aging ovaries, and the overexpression of TET1 can promote proliferation and inhibit apoptosis in aging ovarian cells.

Age-related uterine changes and its association with poor reproductive outcomes: a systematic review and meta-analysis

BACKGROUND

The decline in women's fertility becomes clinically relevant between 35-40 years old, when there is insufficient ovarian activity, and it becomes more difficult to achieve pregnancy naturally and through artificial reproductive technologies. A competent endometrium is required for establishing and maintaining a pregnancy to term, however, experts in the field underestimate the contribution of endometrial age and its impact on reproductive outcomes remains unclear.

STUDY DESIGN

A systematic search of full-text articles available in PubMed was conducted to retrieve relevant studies published until March 2023. Search terms included: endometrium, uterus, age, aging, pregnancy, and oocyte donation. Terms related to reproductive pathologies were excluded. Eligibility criteria included original, rigorous, and accessible peer-reviewed work, published in English on the effect of age on the uterus and endometrium.

RESULTS

From 11,354 records identified, 142 studies were included for systematic review, and 59 were eligible for meta-analysis of endometrial thickness (n = 7), pregnancy rate (n = 22), implantation rate (n = 10), live birth rate (n = 10) and pregnancy loss rate (n = 11). Studies for the meta-analysis of reproductive outcomes only included transfers of embryos from ovum donation (ovum donors < 36 years old). Age shrinks the uterus; depletes endometrial blood supply through narrow uterine veins and a progressive loss of uterine spiral arteries; disrupts endometrial architecture and cellular composition; alters hormone production, shortening menstrual cycle length and impeding endometrial progression to the secretory stage; and dysregulates key endometrial functions such as adhesion, proliferation, apoptosis, and receptivity, among others. Women over 35-40 years old had significantly thinner endometrium (MD 0.52 mm). Advanced maternal age is associated with lower odds of achieving implantation (27%) and clinical pregnancy (20%), or higher odds of experiencing pregnancy loss (44%).

CONCLUSION

Due to the effect of age on endometrium reported in this review, managing patients with advanced maternal age may require considering the endometrial factor as a potential tissue to treat with anti-aging strategies. This review provides researchers and clinicians with an updated and in-depth summary of this topic, encouraging the development of new tailored anti-aging and preventive strategies for precision medicine in endometrial factor in infertility.

TRIAL REGISTRATION

PROSPERO 2023 (CRD42023416947).

Estimation of physiological aging based on routine clinical biomarkers: a prospective cohort study in elderly Chinese and the UK Biobank

BACKGROUND

Chronological age (CA) does not reflect individual variation in the aging process. However, existing biological age predictors are mostly based on European populations and overlook the widespread nonlinear effects of clinical biomarkers.

METHODS

Using data from the prospective Dongfeng-Tongji (DFTJ) cohort of elderly Chinese, we propose a physiological aging index (PAI) based on 36 routine clinical biomarkers to measure aging progress. We first determined the optimal level of each biomarker by restricted cubic spline Cox models. For biomarkers with a U-shaped relationship with mortality, we derived new variables to model their distinct effects below and above the optimal levels. We defined PAI as a weighted sum of variables predictive of mortality selected by a LASSO Cox model. To measure aging acceleration, we defined ΔPAI as the residual of PAI after regressing on CA. We evaluated the predictive value of ΔPAI on cardiovascular diseases (CVD) in the DFTJ cohort, as well as nine major chronic diseases in the UK Biobank (UKB).

RESULTS

In the DFTJ training set (n = 12,769, median follow-up: 10.38 years), we identified 25 biomarkers with significant nonlinear associations with mortality, of which 11 showed insignificant linear associations. By incorporating nonlinear effects, we selected CA and 17 clinical biomarkers to calculate PAI. In the DFTJ testing set (n = 15,904, 5.87 years), PAI predict mortality with a concordance index (C-index) of 0.816 (95% confidence interval, [0.796, 0.837]), better than CA (C-index = 0.771 [0.755, 0.788]) and PhenoAge (0.799 [0.784, 0.814]). ΔPAI was predictive of incident CVD and its subtypes, independent of traditional risk factors. In the external validation set of UKB (n = 296,931, 12.80 years), PAI achieved a C-index of 0.749 (0.746, 0.752) to predict mortality, remaining better than CA (0.706 [0.702, 0.709]) and PhenoAge (0.743 [0.739, 0.746]). In both DFTJ and UKB, PAI calibrated better than PhenoAge when comparing the predicted and observed survival probabilities. Furthermore, ΔPAI outperformed any single biomarker to predict incident risks of eight age-related chronic diseases.

CONCLUSIONS

Our results highlight the potential of PAI and ΔPAI as integrative biomarkers to evaluate aging acceleration and facilitate the development of targeted intervention strategies for healthy aging.

Human Umbilical Cord Mesenchymal Stem Cells Combined with Dehydroepiandrosterone Inhibits Inflammation-Induced Uterine Aging in Mice

With the postponement of the reproductive age of women, the difficulty of embryo implantation caused by uterine aging has become a key factor restricting fertility. However, there are few studies on protective interventions for naturally aging uteri. Although many factors cause uterine aging, such as oxidative stress (OS), inflammation, and fibrosis, their impact on uterine function manifests as reduced endometrial receptivity. This study aimed to use a combination of human umbilical cord mesenchymal stem cells (hUC-MSCs) and dehydroepiandrosterone (DHEA) to delay uterine aging. The results showed that the combined treatment of hUC-MSCs + DHEA increased the number of uterine glandular bodies and the thickness of the endometrium while inhibiting the senescence of endometrial epithelial cells. This combined treatment alleviates the expression of OS (reactive oxygen species, superoxide dismutase, and GSH-PX) and proinflammatory factors (interleukin [IL]-1, IL6, IL-18, and tumor necrosis factor-α) in the uterus, delaying the aging process. The combined treatment of hUC-MSCs + DHEA alleviated the abnormal hormone response of the endometrium, inhibited excessive accumulation and fibrosis of uterine collagen, and upregulated uterine estrogen and progesterone receptors through the PI3K/AKT/mTOR pathway. This study suggests that uterine aging can be delayed through hUC-MSCs + DHEA combination therapy, providing a new treatment method for uterine aging.

[Mechanisms of the Effect of Maternal Age-Related Oocyte Aging on Fertility: Transcriptomic Sequencing Analysis of a Zebrafish Model]

Objective

Female fertility gradually decreases with the increase in women's age. The underlying reasons include the decline in the quantity and quality of oocytes. Oocyte aging is an important manifestation of the decline in oocyte quality, including in vivo oocyte aging before ovulation and in vitro oocyte aging after ovulation. Currently, few studies have been done to examine oocyte aging, and the relevant molecular mechanisms are not fully understood. Therefore, we used zebrafish as a model to investigate oocyte aging. Three different age ranges of female zebrafish were selected to mate with male zebrafish of the best breeding age. In this way, we studied the effects of maternal age-related oocyte aging on fertility and investigated the potential molecular mechanisms behind maternal age-related fertility decline.

Methods

Eight female zebrafish aged between 158 and 195 d were randomly selected for the 6-month age group (180±12) d, 8 female zebrafish aged between 330 and 395 d were randomly selected for the 12-month age group (360±22) d, and 8 female zebrafish aged between 502 and 583 d were randomly selected for the 18-month age group (540±26) d. Male zebrafish of (180±29) d were randomly selected from zebrafish aged between 158 and 195 d and mated with female zebrafish in each group. Each mating experiment included 1 female zebrafish and 1 male zebrafish. Zebrafish embryos produced by the mating experiments were collected and counted. The embryos at 4 hours post-fertilization were observed under the microscope, the total number of embryos and the number of unfertilized embryos were counted, and the fertilization rate was calculated accordingly. The numbers of malformed embryos and dead embryos were counted 24 hours after fertilization, and the rates of embryo malformation and mortality were calculated accordingly. The primary outcome measure was the embryo fertilization rate, and the secondary outcome measures were the number of embryos per spawn (the total number of embryos laid within 1.5 hours after the beginning of mating and reproduction of the zebrafish), embryo mortality, and embryo malformation rate. The outcome measures of each group were compared. The blastocyst embryos of female zebrafish from each group born after mating with male zebrafish in their best breeding period were collected for transcriptomics analysis. Fresh oocytes of female zebrafish in each group were collected for transcriptomics analysis to explore the potential molecular mechanisms of maternal age-related fertility decline.

Results

Compared with that of the 6-month group (94.9%±3.6%), the embryo fertilization rate of the 12-month group (92.3%±4.2%) showed no significant difference, but that of the 18-month group (86.8%±5.5%) decreased significantly (P<0.01). In addition, the fertilization rate in the 18-month group was significantly lower than that in the 12-month group (P<0.05). Compared with that of the 6-month group, the embryo mortality of the female zebrafish in the 12-month group and that in the 18-month group were significantly higher than that in the 6-month group (P<0.000 1, P<0.001). There was no significant difference in the number of embryos per spawn or in the embryo malformation rate among the three groups. The results of the transcriptomics analysis of blastocyst embryos showed that some genes, including dusp5, bdnf, ppip5k2, dgkg, aldh3a2a, acsl1a, hal, mao, etc, were differentially expressed in the 12-month group or the 18-month group compared with their expression levels in the 6-month group. According to the KEGG enrichment analysis, these differentially expressed genes (DEGs) were significantly enriched in the MAPK signaling pathway, the phosphatidylinositol signaling system, and the fatty acid degradation and histidine metabolism pathway (P<0.05). The analysis of the expression trends of the genes expressed differentially among the three groups (the 6-month group, the 12-month group, and the 18-month group in turn) showed that the gene expression trends of fancc, fancg, fancb, and telo2, which were involved in Fanconi anemia pathway, were statistically significant (P<0.05). In the results of oocyte transcriptomics analysis, the genes that were differentially expressed in the 12-month group or the 18-month group compared with the 6-month group were mainly enriched in cell adhesion molecules and the protein digestion and absorption pathway (P<0.05). The results of the trends of gene expression in the zebrafish oocytes of the three groups (the 6-month group, the 12-month group, and the 18-month group in turn) showed that three kinds of gene expression trends of declining fertility with growing maternal age had significant differences (P<0.05). Further analysis of the three significantly differential expression trends showed 51 DEGs related to mitochondria and 5 DEGs related to telomere maintenance and DNA repair, including tomm40, mpc2, nbn, tti1, etc.

Conclusion

With the increase in the maternal age of the zebrafish, the embryo fertilization rate decreased significantly and the embryo mortality increased significantly. In addition, with the increase in the maternal age of the zebrafish, the expression of mitochondria and telomere-related genes, such as tomm40, mpc2, nbn, and tti1, in female zebrafish oocytes decreased gradually. Maternal age may be a factor contributing to the decrease in oocyte fertilization ability and the increase in early embryo mortality. Maternal age-related oocyte aging affects the fertility and embryo development of the offspring.

Omics-based novel strategies in the diagnosis of endometriosis

Endometriosis, an enigmatic and chronic disorder, is considered a debilitating condition despite being benign. Globally, this gynecologic disorder affects up to 10% of females of reproductive age, impacting almost 190 million individuals. A variety of genetic and environmental factors are involved in endometriosis development, hence the pathophysiology and etiology of endometriosis remain unclear. The uncertainty of the etiology of the disease and its complexity along with nonspecific symptoms have led to misdiagnosis or lack of diagnosis of affected people. Biopsy and laparoscopy are referred to as the gold standard for endometriosis diagnosis. However, the invasiveness of the procedure, the unnecessary operation in disease-free women, and the dependence of the reliability of diagnosis on experience in this area are considered the most significant limitations. Therefore, continuous studies have attempted to offer a noninvasive and reliable approach. The recent advances in modern technologies have led to the generation of large-scale biological data sets, known as -omics data, resulting in the proceeding of the -omics century in biomedical sciences. Thereby, the present study critically reviews novel and noninvasive biomarkers that are based on -omics approaches from 2020 onward. The findings reveal that biomarkers identified based on genomics, epigenomics, transcriptomics, proteomics, and metabolomics are potentially able to diagnose endometriosis, predict prognosis, and stage patients, and potentially, in the near future, a multi-panel of these biomarkers will generate clinical benefits.

Gonadotropins Regulate the mRNA Expression of Gonadotropin-Releasing Hormone and Its Receptors in the Mouse Ovary and Uterus

Gonadotropin-releasing hormone (GnRH), a critical hormone produced in the hypothalamus, is essential for regulating reproductive processes. It has also been demonstrated the presence of GnRH and its receptors (GnRHR) in ovarian and uterine tissues, but little was known about the regulation mechanism of their expression in these organs and ovarian aging. Therefore, the aim of this study was to investigate the expression of GnRHR in the ovary and uterus of mice, particularly after high-dose gonadotropin treatments and in relation to aging. Quantitative real-time-PCR (qRT-PCR) revealed that pituitary gland had the highest GnRHR expression in both young and aged mice. In addition, liver expression was higher in young mice, whereas thymus expression was higher in aged mice. GnRHR mRNA was present in the ovaries of both young and aged mice but nearly undetectable in the uterus of aged mice. We next examined the expression of GnRHR in the ovary and uterus in response to high-dose administration of pregnant mare serum gonadotropin (PMSG). After PMSG administration, GnRH mRNA levels were significantly decreased in the ovary but increased in the uterus. The expression of GnRH mRNA in these organs showed opposite trends to that of GnRHR expression. These results suggest the involvement of GnRH in age-related reproductive decline and the potential effects of high-dose gonadotropin treatments on reproductive organ function.

Endometrial receptivity in women of advanced age: an underrated factor in infertility

BACKGROUND

Modern lifestyle has led to an increase in the age at conception. Advanced age is one of the critical risk factors for female-related infertility. It is well known that maternal age positively correlates with the deterioration of oocyte quality and chromosomal abnormalities in oocytes and embryos. The effect of age on endometrial function may be an equally important factor influencing implantation rate, pregnancy rate, and overall female fertility. However, there are only a few published studies on this topic, suggesting that this area has been under-explored. Improving our knowledge of endometrial aging from the biological (cellular, molecular, histological) and clinical perspectives would broaden our understanding of the risks of age-related female infertility.

OBJECTIVE AND RATIONALE

The objective of this narrative review is to critically evaluate the existing literature on endometrial aging with a focus on synthesizing the evidence for the impact of endometrial aging on conception and pregnancy success. This would provide insights into existing gaps in the clinical application of research findings and promote the development of treatment options in this field.

SEARCH METHODS

The review was prepared using PubMed (Medline) until February 2023 with the keywords such as 'endometrial aging', 'receptivity', 'decidualization', 'hormone', 'senescence', 'cellular', 'molecular', 'methylation', 'biological age', 'epigenetic', 'oocyte recipient', 'oocyte donation', 'embryo transfer', and 'pregnancy rate'. Articles in a language other than English were excluded.

OUTCOMES

In the aging endometrium, alterations occur at the molecular, cellular, and histological levels suggesting that aging has a negative effect on endometrial biology and may impair endometrial receptivity. Additionally, advanced age influences cellular senescence, which plays an important role during the initial phase of implantation and is a major obstacle in the development of suitable senolytic agents for endometrial aging. Aging is also accountable for chronic conditions associated with inflammaging, which eventually can lead to increased pro-inflammation and tissue fibrosis. Furthermore, advanced age influences epigenetic regulation in the endometrium, thus altering the relation between its epigenetic and chronological age. The studies in oocyte donation cycles to determine the effect of age on endometrial receptivity with respect to the rates of implantation, clinical pregnancy, miscarriage, and live birth have revealed contradictory inferences indicating the need for future research on the mechanisms and corresponding causal effects of women's age on endometrial receptivity.

WIDER IMPLICATIONS

Increasing age can be accountable for female infertility and IVF failures. Based on the complied observations and synthesized conclusions in this review, advanced age has been shown to have a negative impact on endometrial functioning. This information can provide recommendations for future research focusing on molecular mechanisms of age-related cellular senescence, cellular composition, and transcriptomic changes in relation to endometrial aging. Additionally, further prospective research is needed to explore newly emerging therapeutic options, such as the senolytic agents that can target endometrial aging without affecting decidualization. Moreover, clinical trial protocols, focusing on oocyte donation cycles, would be beneficial in understanding the direct clinical implications of endometrial aging on pregnancy outcomes.

Flip a coin: cell senescence at the maternal-fetal interface†

During pregnancy, cell senescence at the maternal-fetal interface is required for maternal well-being, placental development, and fetal growth. However, recent reports have shown that aberrant cell senescence is associated with multiple pregnancy-associated abnormalities, such as preeclampsia, fetal growth restrictions, recurrent pregnancy loss, and preterm birth. Therefore, the role and impact of cell senescence during pregnancy requires further comprehension. In this review, we discuss the principal role of cell senescence at the maternal-fetal interface, emphasizing its "bright side" during decidualization, placentation, and parturition. In addition, we highlight the impact of its deregulation and how this "dark side" promotes pregnancy-associated abnormalities. Furthermore, we discuss novel and less invasive therapeutic practices associated with the modulation of cell senescence during pregnancy.

Epigenetic clocks and female fertility timeline: A new approach to an old issue?

Worldwide increase in life expectancy has boosted research on aging. Overcoming the concept of chronological age, higher attention has been addressed to biological age, which reflects a person's real health state, and which may be the resulting combination of both intrinsic and environmental factors. As epigenetics may exert a pivotal role in the biological aging, epigenetic clocks were developed. They are based on mathematical models aimed at identifying DNA methylation patterns that can define the biological age and that can be adopted for different clinical scopes (i.e., estimation of the risks of developing age-related disorders or predicting lifespan). Recently, epigenetic clocks have gained a peculiar attention in the fertility research field, in particular in the female counterpart. The insight into the possible relations between epigenetic aging and women's infertility might glean additional information about certain conditions that are still not completely understood. Moreover, they could disclose significant implications for health promotion programs in infertile women. Of relevance here is that the impact of biological age and epigenetics may not be limited to fertility status but could translate into pregnancy issues. Indeed, epigenetic alterations of the mother may transfer into the offspring, and pregnancy itself as well as related complications could contribute to epigenetic modifications in both the mother and newborn. However, even if the growing interest has culminated in the conspicuous production of studies on these topics, a global overview and the availability of validated instruments for diagnosis is still missing. The present narrative review aims to explore the possible bonds between epigenetic aging and fertility timeline. In the "infertility" section, we will discuss the advances on epigenetic clocks focusing on the different tissues examined (endometrium, peripheral blood, ovaries). In the "pregnancy" section, we will discuss the results obtained from placenta, umbilical cord and peripheral blood. The possible role of epigenetic aging on infertility mechanisms and pregnancy outcomes represents a question that may configure epigenetic clock as a bond between two apparently opposite worlds: infertility and pregnancy.

Differentially Expressed Genes and Molecular Susceptibility to Human Age-Related Diseases

Mainstream transcriptome profiling of susceptibility versus resistance to age-related diseases (ARDs) is focused on differentially expressed genes (DEGs) specific to gender, age, and pathogeneses. This approach fits in well with predictive, preventive, personalized, participatory medicine and helps understand how, why, when, and what ARDs one can develop depending on their genetic background. Within this mainstream paradigm, we wanted to find out whether the known ARD-linked DEGs available in PubMed can reveal a molecular marker that will serve the purpose in anyone's any tissue at any time. We sequenced the periaqueductal gray (PAG) transcriptome of tame versus aggressive rats, identified rat-behavior-related DEGs, and compared them with their known homologous animal ARD-linked DEGs. This analysis yielded statistically significant correlations between behavior-related and ARD-susceptibility-related fold changes (log₂ values) in the expression of these DEG homologs. We found principal components, PC1 and PC2, corresponding to the half-sum and the half-difference of these log₂ values, respectively. With the DEGs linked to ARD susceptibility and ARD resistance in humans used as controls, we verified these principal components. This yielded only one statistically significant common molecular marker for ARDs: an excess of Fcγ receptor IIb suppressing immune cell hyperactivation.