Inflammaging is associated with shifted macrophage ontogeny and polarization in the aging mouse ovary

Menopause mysteries: the exosome-inflammation connection

Extracellular vesicles, or exosomes, are produced by every type of cell and contain metabolites, proteins, lipids, and nucleic acids. Their role in health and disease is to influence different aspects of cell biology and to act as intermediaries between cells. Follicular fluid exosomes or extracellular vesicles (FF-EVs) secreted by ovarian granulosa cells are critical mediators of ovary growth and maturation. The movement and proteins of these exosomes are crucial in the regulation of cellular communication and the aging of cells, a process termed inflammaging. Menopause, a natural progression in the aging of females, is often accompanied by numerous negative symptoms and health issues. It can also act as a precursor to more severe health problems, including neurological, cardiovascular, and metabolic diseases, as well as gynecological cancers. Researchers have discovered pathways that reveal the diverse effects of exosome-driven cellular communication and oocyte development in the follicular fluid. It also explores the complex functions of FF exosomal proteins in the pathologies associated with menopause.

Immune system regulation of physiological and pathological aspects of the ovarian follicle pool throughout the female reproductive lifespan

The immune system plays a major role in ovarian physiology by regulating the ovarian follicle pool through complex signaling of different growth factors, cytokines, and chemokines. These may promote follicle activation and further growth but could also trigger follicle atresia and clearance of aging or damaged cells within the ovarian cortex. Moreover, extraglandular steroidogenesis potentially occurring in different immune cells like macrophages and natural killer cells might be another way of modulating follicle growth. Ovarian macrophages have recently been found to contain two different populations, namely resident macrophages and monocyte-derived cells, with potentially different roles. The immune system also plays a role in the development of pathological conditions, including premature ovarian insufficiency (POI). Indeed, autoimmune activation against various ovarian antigen targets results in lymphocytic oophoritis mainly targeting early growing follicles, but later leading to complete follicle pool depletion. Immune-mediated ovarian damage may also be caused by viral infection or be the consequence of iatrogenic damage. Certain novel cancer immunotherapies like checkpoint inhibitors have recently been shown to induce ovarian reserve damage in a murine model. Studies are needed to corroborate these findings and further investigate the potential of newly developed immunotherapies to treat POI. Technological advances such as single-cell analyses of less represented cell populations like immune cells inside the ovary are now contributing to valuable new information, which will hopefully lead to the development of new therapeutic strategies for women with fertility issues.

Can ultrasound elastography be useful in the diagnosis of poor ovarian response?

OBJECTIVES

This study aims to compare the elastographic properties of the ovaries of patients with poor ovarian response (POR) with healthy controls by using real-time ultrasound tissue elastography and to investigate the predictive value of ovarian strain ratio (OSR) in the diagnosis of POR.

MATERIALS AND METHODS

A cross-sectional study was conducted among infertility patients. OSR measurements of 46 women diagnosed with POR and 41 healthy controls with male infertility were performed by real-time ultrasound tissue elastography. Ovarian volume, OSR, antral follicle count (AFC), age, body mass index (BMI), anti-mullerian hormone (AMH), follicle stimulating hormone (FSH), and estradiol (E2) values, were compared between the groups. A receiver operating characteristic curve was used to compare the sensitivity and specificity of OSR, AFC, AMH, FSH, and E2 for POR diagnosis.

RESULTS

Patients with POR were significantly older, had a lower duration of infertility, lower AMH, higher FSH, higher E2, lower AFC and ovarian volume (p < 0.01, p = 0.02, p < 0.01, p < 0.01, p < 0.01, p < 0.01, p < 0.01, respectively). The mean OSR of both ovaries was similar between the groups. For the diagnosis of POR, the sensitivity and specificity for AMH were 97.5% and 100%, for AFC were 86.7% and 97.6%; for FSH were 66.7% and 80.5%, for E2 were 53.3% and 90.2%, respectively.

CONCLUSIONS

The significant independent predictors of the POR were AMH, AFC, and FSH, with no additional significant contribution from OSR. However, considering the relationship between POR and ovarian fibrosis, it is recommended to investigate this issue in more comprehensive studies.

Age-associated aberrations of the cumulus-oocyte interaction and in the zona pellucida structure reduce fertility in female mice

One of the major age-related declines in female reproductive function is the reduced quantity and quality of oocytes. Here we demonstrate that structural changes in the zona pellucida (ZP) were associated with decreased fertilization rates from 34- to 38-week-old female mice, equivalent to the mid-reproductive of human females. In middle-aged mouse ovaries, the decline in the number of transzonal projections was accompanied by a decrease in cumulus cell-oocyte interactions, resulting in a deterioration of the oocyte quality. Scanning electron microscopy showed the ZP surface microfilament structure transitioning from rugged to smooth with aging, leading to decreased fertilization rates due to impaired sperm binding to the ZP. Moreover, the fertilization rate of middle-aged mice was restored to a comparable level to that of young mice by destabilizing the ZP in the presence of glutathione. These results suggest that the age-related structural changes in the ZP are key for successful fertilization at reproductive age.

Altered Immune Cell Profiles in the Follicular Fluid of Patients with Poor Ovarian Response According to the POSEIDON Criteria

Objective

This study aims to investigate alterations in immune cell counts within preovulatory follicles of patients with poor ovarian response (POR) during assisted reproductive technology (ART), classified according to the POSEIDON criteria.

Methods

This single-centre cross-sectional study included 543 women undergoing IVF/ICSI treatment, selected based on specific inclusion and exclusion criteria: 292 with normal ovarian response and 251 with poor response. Follicular fluid (FF) was collected on the day of oocyte retrieval and analysed by flow cytometry to determine the proportions of macrophages (Mφs), M1 and M2 Mφs, T cells (CD4 and CD8 T cells), dendritic cells (DCs), including type 1 conventional dendritic cells (cDC1) and type 2 conventional dendritic cells (cDC2), and neutrophils. Multivariable logistic regression assessed the relationship between immune cell counts and POR, Pearson correlation determined associations with the number of retrieved oocytes, and receiver operating characteristic (ROC) curves evaluated the predictive power of immune cell counts for POR.

Results

Immune cells accounted for 52.57% (±23.90%) of the total cell population in the follicular microenvironment, which was approximately equal to that of granulosa cells, with Mφs being the most abundant, followed sequentially by T cells, DCs, and neutrophils. In patients with POR, overall Mφs infiltration in the follicular microenvironment decreased, whereas M1 and M2 polarization increased. T cell infiltration increased, with a decrease in the CD4/CD8 ratio. Both cDC1 and cDC2 were significantly elevated. Moreover, multivariable logistic regression revealed that the total macrophage count, CD4 T cell count, and cDC2 count were independent predictors of POR. Notably, cDC2 showed the largest area under the ROC curve, suggesting its strong potential as a biomarker for predicting POR.

Conclusion

The proportion of immune cells in preovulatory follicles were significantly altered in patients with POR. These findings suggest that immune cell dynamics in the follicular microenvironment may play a crucial role in determining ovarian response and prognosis, indicating that targeted immunomodulatory strategies could be considered in future therapeutic approaches.

IL-33 and soluble ST2 in follicular fluid are associated with premature ovarian insufficiency

Background

Premature ovarian insufficiency (POI) is a common reproductive disease that is associated with chronic inflammation in ovaries. Interleukin 33 (IL-33) is a pro-inflammatory IL-1 family cytokine, and functions as an alarmin reflecting inflammatory reaction. Our study aimed to investigate levels of IL-33 and its soluble receptor (sST2) in both follicular fluid (FF) and paired serum during different stages of POI, and evaluate their predictive potentials for POI. Furthermore, we attempted to determine whether IL-33 and sST2 were associated with embryo quality.

Methods

A total of 148 women, including 50 patients with biochemical POI (bPOI) (10 IU/L < follicle-stimulating hormone (FSH) ≤ 25 IU/L), 46 patients with POI (25 IU/L

Results

FF IL-33 levels were significantly increased in bPOI and POI patients compared to controls. They exhibited positive associations with FSH and luteinizing hormone (LH), whereas negative correlations with anti-Müllerian hormone (AMH), estradiol (E2), testosterone (T) and antral follicle count (AFC). Receiver operating characteristic (ROC) curve analysis showed that for POI prediction, FF IL-33 had a better predictive accuracy (AUC 0.901) with high sensitivity (82.61%) and good specificity (84.62%) than those for bPOI prediction. IL-33 levels in paired serum did not differ among three groups. Regarding sST2, its levels in FF declined with POI progression. Contrarily, they showed negative associations with FSH and LH, but positive correlations with AMH, E2, T and AFC. ROC analysis revealed that FF sST2 had comparatively weak potentials for both bPOI and POI prediction compared to those of FF IL-33. Similarly, there was no significant alteration of sST2 in paired serum among three groups. Additionally, Spearman's correlation analysis revealed that FF IL-33 levels were negatively associated with the rates of Day-3 good-quality embryos (r=-0.206, P=0.012), whereas FF sST2 did not.

Conclusion

Our study revealed an increased abundance of FF IL-33, whereas an sST2 deficiency with POI development. This implies that IL-33 and sST2 levels might be associated with the development of POI.

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Key Words

• IL-33
• embryo development
• embryo quality
• inflammation
• ovarian reserve
• predictor
• premature ovarian insufficiency
• soluble ST2

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MESH Headings

• Humans
• Female
• Interleukin-33/blood
• Interleukin-33/metabolism
• Interleukin-1 Receptor-Like 1 Protein/blood
• Interleukin-1 Receptor-Like 1 Protein/metabolism
• Follicular Fluid/metabolism
• Primary Ovarian Insufficiency/blood
• Primary Ovarian Insufficiency/metabolism
• Adult
• Biomarkers/blood
• Biomarkers/metabolism
• Biomarkers/analysis
• Follicle Stimulating Hormone/blood
• Follicle Stimulating Hormone/metabolism
• Case-Control Studies

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Affiliation(s)

Maoxing Tang Department of Reproductive Medicine, Guangdong Provincial People’s Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, China
Xuedong Sun Department of Neurology, Nanfang Hospital, Southern Medical University, Guangzhou, China
Ping Li Department of Reproductive Medicine, Women and Children’s Hospital, School of Medicine, Xiamen University, Xiamen, China
Weifen Deng Reproductive Medicine Centre, Shenzhen Hengsheng Hospital, Shenzhen, China
Xi Zhan Department of Reproductive Medicine, Guangdong Provincial People’s Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, China
Peng Sun Department of Reproductive Medicine, Guangdong Provincial People’s Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, China
Yuhua Shi Department of Obstetrics and Gynecology, Center for Reproductive Medicine, Nanfang Hospital, Southern Medical University, Guangzhou, China

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Multinucleated giant cells are hallmarks of ovarian aging with unique immune and degradation-associated molecular signatures

The ovary is one of the first organs to exhibit signs of aging, characterized by reduced tissue function, chronic inflammation, and fibrosis. Multinucleated giant cells (MNGCs), formed by macrophage fusion, typically occur in chronic immune pathologies, including infectious and non-infectious granulomas and the foreign body response 1 , but are also observed in the aging ovary 2-4 . The function and consequence of ovarian MNGCs remain unknown as their biological activity is highly context-dependent, and their large size has limited their isolation and analysis through technologies such as single-cell RNA sequencing. In this study, we define ovarian MNGCs through a deep analysis of their presence across age and species using advanced imaging technologies as well as their unique transcriptome using laser capture microdissection. MNGCs form complex interconnected networks that increase with age in both mouse and nonhuman primate ovaries. MNGCs are characterized by high Gpnmb expression, a putative marker of ovarian and non-ovarian MNGCs 5,6 . Pathway analysis highlighted functions in apoptotic cell clearance, lipid metabolism, proteolysis, immune processes, and increased oxidative phosphorylation and antioxidant activity. Thus, MNGCs have signatures related to degradative processes, immune function, and high metabolic activity. These processes were enriched in MNGCs compared to primary ovarian macrophages, suggesting discrete functionality. MNGCs express CD4 and colocalize with T-cells, which were enriched in regions of MNGCs, indicative of a close interaction between these immune cell types. These findings implicate MNGCs in modulation of the ovarian immune landscape during aging given their high penetrance and unique molecular signature that supports degradative and immune functions.

SenNet recommendations for detecting senescent cells in different tissues

Once considered a tissue culture-specific phenomenon, cellular senescence has now been linked to various biological processes with both beneficial and detrimental roles in humans, rodents and other species. Much of our understanding of senescent cell biology still originates from tissue culture studies, where each cell in the culture is driven to an irreversible cell cycle arrest. By contrast, in tissues, these cells are relatively rare and difficult to characterize, and it is now established that fully differentiated, postmitotic cells can also acquire a senescence phenotype. The SenNet Biomarkers Working Group was formed to provide recommendations for the use of cellular senescence markers to identify and characterize senescent cells in tissues. Here, we provide recommendations for detecting senescent cells in different tissues based on a comprehensive analysis of existing literature reporting senescence markers in 14 tissues in mice and humans. We discuss some of the recent advances in detecting and characterizing cellular senescence, including molecular senescence signatures and morphological features, and the use of circulating markers. We aim for this work to be a valuable resource for both seasoned investigators in senescence-related studies and newcomers to the field.

Association of different inflammatory indices with risk of early natural menopause: a cross-sectional analysis of the NHANES 2013-2018

Background

Early natural menopause, characterized by the cessation of ovarian function before the age of 45, has been a subject of prior research indicating that inflammation may predict the onset of menopause. However, the specific relationship between peripheral blood inflammatory parameters and early natural menopause remains ambiguous.

Methods

This observational study utilized data from the National Health and Nutrition Examination Survey (NHANES) spanning the years 2013-2018. The age at menopause was ascertained through the Reproductive Health Questionnaire (RHQ), with early natural menopause defined as menopause occurring before the age of 45 years. Complete blood counts were derived from laboratory test data, and seven indices of inflammation were calculated, including lymphocyte count (LC), neutrophil count (NC), systemic immune inflammation index (SII), product of platelet and neutrophil count (PPN), platelet-lymphocyte ratio (PLR), neutrophil-lymphocyte ratio (NLR), and lymphocyte-monocyte ratio (LMR). A multivariate weighted logistic regression analysis was employed to estimate the association between these inflammatory indices and early natural menopause.

Results

A total of 2,034 participants were included in the analysis, of whom 460 reported experiencing menopause before the age of 45. Both Log2-NC and Log2-PPN were found to be positively correlated with early menopause, with odds ratios (OR) of 1.56 (95% CI: 1.16, 2.09; p = 0.005) and 1.36 (95% CI: 1.07, 1.72; p = 0.015), respectively. The results from models 1 and 2 were consistent with those from model 3. In the trend test, participants in the fourth quartile (Q4) of log2-LC exhibited a positive correlation with early menopause compared to those in the lowest quartile (Q1), with an OR of 1.41 (95% CI: 1.03, 1.93; p = 0.033). Similarly, the fourth quartile (Q4) of log2-NC and log2-PPN demonstrated a positive correlation with early menopause, with odds ratios (OR) of 1.76 (95% CI: 1.27-2.45; p < 0.001) and 1.66 (95% CI: 1.21-2.29; p = 0.002), respectively. In Model 3, log2-SII, log2-PLR, log2-NLR, and log2-LMR were not significantly associated with early menopause.

Conclusion

Our findings indicate that elevated levels of Log2-LC, Log2-NC, and Log2-PPN are positively correlated with an increased risk of early menopause among women in the United States.

Combined targeting of senescent cells and senescent macrophages: A new idea for integrated treatment of lung cancer

Lung cancer is one of the most common cancers worldwide and a leading cause of cancer-related deaths. Macrophages play a key role in the immune response and the tumour microenvironment. As an important member of the immune system, macrophages have multiple functions, including phagocytosis and clearance of pathogens, modulation of inflammatory responses, and participation in tissue repair and regeneration. In lung cancer, macrophages are considered to be the major cellular component of the tumor-associated inflammatory response and are closely associated with tumorigenesis, progression and metastasis. However, macrophages gradually undergo a senescence process with age and changes in pathological states. Macrophage senescence is an important change in the functional and metabolic state of macrophages and may have a significant impact on lung cancer development. In lung cancer, senescent macrophages interact with other cells in the tumor microenvironment (TME) by secreting senescence-associated secretory phenotype (SASP) factors, which can either promote the proliferation, invasion and metastasis of tumor cells or exert anti-tumor effects through reprogramming or clearance under specific conditions. Therefore, senescent macrophages are considered important potential targets for lung cancer therapy. In this paper, a systematic review of macrophages and their senescence process, and their role in tumors is presented. A variety of inhibitory strategies against senescent macrophages, including enhancing autophagy, inhibiting SASP, reducing DNA damage, and modulating metabolic pathways, were also explored. These strategies are expected to improve lung cancer treatment outcomes by restoring the anti-tumor function of macrophages.

Accumulated inflammation and fibrosis participate in atrazine induced ovary toxicity in mice

Atrazine is a widely used herbicide in agricultural production. Previous studies have shown that atrazine affects hormone secretion and oocyte maturation in female reproduction. However, the specific mechanism by which atrazine affects ovarian function remains unclear. In this study, using a mouse gastric lavage model, we report that four weeks of atrazine exposure affects body growth, interferes with the estrous cycle, and increases the number of atretic follicles in mice. The expression levels of follicle development related factors StAR, BMP15, and AMH decreased. Metabolomic analysis revealed that atrazine activates an inflammatory response in ovarian tissue. Further studies confirmed that the expression levels of TNF-α, IL-6, and NF-κB increased in the ovaries of mice exposed to atrazine. Additionally, α-smooth muscle actin (α-SMA) accumulated in ovarian tissue, and transforming growth factor-β (TGF-β) signaling was activated, indicating the occurrence of tissue fibrosis. Moreover, mice exposed to atrazine produced fewer oocytes and exhibited reduced embryonic development. Furthermore, mice exposed to atrazine exhibited altered gut microbiota abundance and a disrupted colon barrier. Collectively, these findings suggest that atrazine exposure induces ovarian inflammation and fibrosis, disrupts ovarian homeostasis, and impairs follicle maturation, ultimately reducing oocyte quality.

Advances in cytokine-based herbal medicine against premature ovarian insufficiency: A review

ETHNOPHARMACOLOGICAL RELEVANCE

Premature ovarian insufficiency (POI) refers to a dramatic decrease in the number and/or quality of oocytes in the ovaries before the age of 40 years, and is a key cause of female infertility. The prevalence of POI has been increasing annually and tends to be younger. Researches on the etiology of POI and related pathogenesis are still very limited. Herbal medicine can treat many gynecological diseases. And herbal medicine is effective in reproductive health care such as infertility. In recent years, it has been found that immune modulation by cytokines (CK) can prevent or intervene in POI, and herbal medicine can treat POI by regulating CK to improve ovarian function and fertility.

AIM OF THE STUDY

This review presents an overview of the molecular mechanisms of regulation of POI related CK, and reports the therapeutic effect of herbal medicine on POI including herbal medicine formulas, single herbal medicine, herbal medicine active components and acupuncture. This review provides theoretical support for clinical prevention and treatment of POI, and provides new ideas for researches on herbal medicine treatment of POI.

MATERIALS AND METHODS

We performed a collection of relevant scientific articles from different scientific databases regarding the therapeutic effect of herbal medicine on POI by regulating CK, including PubMed, Web of Science, Wanfang Database, CNKI and other publication resources. The search terms used in this review include, 'premature ovarian insufficiency', 'premature ovarian failure (POF)', 'infertility', 'herbal medicine', 'acupuncture', 'cytokine', 'interleukin (IL)', 'tumor necrosis factor-α (TNF-α)', 'interferon-γ (IFN-γ)', 'transforming growth factor-β (TGF-β)', 'vascular endothelial growth factor (VEGF)', 'immune' and 'inflammation'. This review summarized and analyzed the therapeutic effect of herbal medicine according to the existing experimental and clinical researches.

RESULTS

The results showed that herbal medicine treats POI through CK (including ILs, TNF-α, INF-γ, VEGF, TGF-β and others) and related signaling pathways, which regulates reproductive hormones disorder, reduces ovarian inflammatory damage, oxidative stress, apoptosis and follicular atresia, improves ovarian pathological damage and ovarian reserve function.

CONCLUSIONS

This review enriches the theory of POI treatments based on herbal medicine by regulating CK. The specific mechanisms of action and clinical researches on the treatment of POI by herbal medicine should be strengthened in order to promote the application of herbal medicine in the clinic and provide new ideas and better choices for the treatment of POI.

Systemic low-dose anti-fibrotic treatment attenuates ovarian aging in the mouse

The female reproductive system is one of the first to age in humans, resulting in infertility and endocrine disruptions. The aging ovary assumes a fibro-inflammatory milieu which negatively impacts gamete quantity and quality as well as ovulation. Here, we tested whether the systemic delivery of anti-inflammatory (Etanercept) or anti-fibrotic (Pirfenidone) drugs attenuates ovarian aging in mice. We first evaluated the ability of these drugs to decrease the expression of fibro-inflammatory genes in primary ovarian stromal cells treated with a pro-fibrotic or a pro-inflammatory stimulus. Whereas Etanercept did not block Tnf expression in ovarian stromal cells, Pirfenidone significantly reduced Col1a1 expression. We then tested Pirfenidone in vivo where the drug was delivered systemically via mini-osmotic pumps for 6 weeks. Pirfenidone mitigated the age-dependent increase in ovarian fibrosis without impacting overall health parameters. Ovarian function was improved in Pirfenidone-treated mice as evidenced by increased follicle and corpora lutea number, AMH levels, and improved estrous cyclicity. Transcriptomic analysis revealed that Pirfenidone treatment resulted in an upregulation of reproductive function-related genes at 8.5 months and a downregulation of inflammatory genes at 12 months of age. These findings demonstrate that reducing the fibroinflammatory ovarian microenvironment improves ovarian function, thereby supporting modulating the ovarian environment as a therapeutic avenue to extend reproductive longevity.

Prenatal exposure to an environmentally relevant phthalate mixture alters serum cytokine levels and inflammatory markers in the F1 mouse ovary

Phthalates are used as plasticizers and solvents in consumer products. Virtually 100% of the US population has measurable exposure levels to phthalates, however, the mechanisms by which prenatal exposure to phthalate mixtures affects reproductive health in the offspring remain unclear. Thus, this study tested the hypothesis that prenatal exposure to an environmentally relevant phthalate mixture promotes inflammation in F1 ovarian tissue. Pregnant CD-1 dams were dosed orally with vehicle control (corn oil) or phthalate mixture (20 μg/kg/d, 200 μg/kg/d, 200 mg/kg/d, 500 mg/kg/d). Pregnant dams delivered pups naturally and ovaries and sera from the F1 females were collected at postnatal day (PND) 21, PND 60, 3 mo, and 6 mo. Sera were used to measure levels of C-reactive protein (CRP). Ovaries and sera were used for cytokine array analysis. RNA was isolated from F1 ovaries and used to quantify expression of selected cytokine genes. Prenatal exposure to the mixture significantly increased the levels of CRP at 200 µg/kg/d on PND 21 compared with controls. The mixture altered 6 immune factors in sera at PND 21 and 33 immune factors in the ovary and sera at 6 mo compared with controls. The mixture increased ovarian expression of cytokines at PND 21 and decreased ovarian expression of cytokines at 6 mo compared with controls. These data suggest that prenatal exposure to a phthalate mixture interferes with the immune response in F1 female mice long after initial exposure.

METTL3 deficiency leads to ovarian insufficiency due to IL-1β overexpression in theca cells

Premature ovarian insufficiency (POI) is a clinical syndrome characterised by a decline in ovarian function in women before 40 years of age and is associated with oestradiol deficiency and a complex pathogenesis. However, the aetiology of POI is still unclear and effective preventative and treatment strategies are still lacking. Methyltransferase like 3 (METTL3) is an RNA methyltransferase that is involved in spermatogenesis, oocyte development and maturation, early embryonic development, and embryonic stem cell differentiation and formation, but its role in POI is unknown. In the present study, METTL3 deficiency in follicular theca cells was found to lead to reduced fertility in female mice, with a POI-like phenotype, and METTL3 knockout promoted ovarian inflammation. Further, a reduction in METTL3 in follicular theca cells led to a decrease in the m6A modification of pri-miR-21, which further reduced pri-miR-21 recognition and binding by DGCR8 proteins, leading to a decrease in the synthesis of mature miR-21-5p. Decrease of miR-21-5p promoted the secretion of interleukin-1β (IL-1β) from follicular theca cells. Acting in a paracrine manner, IL-1β inhibited the cAMP-PKA pathway and activated the NF-κB pathway in follicular granulosa cells. This activation increased the levels of reactive oxygen species in granulosa cells, causing disturbances in the intracellular Ca2+ balance and mitochondrial damage. These cellular events ultimately led to granulosa cell apoptosis and a decrease in oestradiol synthesis, resulting in POI development. Collectively, these findings reveal how METTL3 deficiency promotes the expression and secretion of IL-1β in theca cells, which regulates ovarian functions, and proposes a new theory for the development of POI disease.

Self-organizing ovarian somatic organoids preserve cellular heterogeneity and reveal cellular contributions to ovarian aging

Ovarian somatic cells are essential for reproductive function, but no existing ex vivo models recapitulate the cellular heterogeneity or interactions within this compartment. We engineered a novel ovarian somatic organoid model by culturing a stroma-enriched fraction of mouse ovaries in scaffold-free agarose micromolds. Ovarian somatic organoids self-organized, maintained diverse cell populations, produced extracellular matrix, and secreted hormones. Organoids generated from reproductively old mice exhibited reduced aggregation and growth compared to young counterparts, as well as differences in cellular composition. Interestingly, matrix fibroblasts from old mice demonstrated upregulation of pathways associated with the actin cytoskeleton and downregulation of cell adhesion pathways, indicative of increased cellular stiffness which may impair organoid aggregation. Cellular morphology, which is regulated by the cytoskeleton, significantly changed with age and in response to actin depolymerization. Moreover, actin depolymerization rescued age-associated organoid aggregation deficiency. Overall, ovarian somatic organoids have advanced fundamental knowledge of cellular contributions to ovarian aging.

Unveiling the role of chronic inflammation in ovarian aging: insights into mechanisms and clinical implications

Ovarian aging, a natural process in women and various other female mammals as they age, is characterized by a decline in ovarian function and fertility due to a reduction in oocyte reserve and quality. This phenomenon is believed to result from a combination of genetic, hormonal, and environmental factors. While these factors collectively contribute to the shaping of ovarian aging, the substantial impact and intricate interplay of chronic inflammation in this process have been somewhat overlooked in discussions. Chronic inflammation, a prolonged and sustained inflammatory response persisting over an extended period, can exert detrimental effects on tissues and organs. This review delves into the novel hallmark of aging-chronic inflammation-to further emphasize the primary characteristics of ovarian aging. It endeavors to explore not only the clinical symptoms but also the underlying mechanisms associated with this complex process. By shining a spotlight on chronic inflammation, the aim is to broaden our understanding of the multifaceted aspects of ovarian aging and its potential clinical implications.

Assessing the effect of adipose-tissue-derived stem cell conditioned medium on follicles and stromal cells in bovine ovarian tissue culture

RESEARCH QUESTION

Does adipose-tissue-derived stem cell conditioned medium (ASC-CM) supplementation enhance follicle and stromal cell outcomes in vitro?

DESIGN

Bovine ovaries (n = 8) were sectioned and cultured in vitro for 8 days in two different groups: (i) standard culture (OT Ctrl D8); and (ii) culture with ASC-CM supplementation (OT + CM D8). Half of the culture medium was replaced every other day, and stored to measure the production of oestradiol. Follicle classification was established using haematoxylin and eosin staining. Follicle and stromal cell DNA fragmentation was assessed by TUNEL assays, while growth differentiation factor-9 (GDF-9) staining served as a marker of follicle quality. Additionally, three factors, namely vascular endothelial growth factor (VEGF), interleukin 6 (IL-6) and transforming growth factor beta 1 (TGF-β1), were evaluated in ASC-CM in order to appraise the potential underlying mechanisms of action of ASC.

RESULTS

The OT + CM D8 group showed a significantly higher proportion of secondary follicles (P = 0.02) compared with the OT Ctrl D8 group. The OT + CM D8 group also demonstrated significantly lower percentages of TUNEL-positive follicles (P = 0.014) and stromal cells (P = 0.001) compared with the OT Ctrl D8 group. Furthermore, follicles in the OT + CM D8 group exhibited a significant increase (P = 0.002) in expression of GDF-9 compared with those in the OT Ctrl D8 group, and oestradiol production was significantly higher (P = 0.04) in the OT + CM D8 group. All studied factors were found to be present in ASC-CM. VEGF and IL-6 were the most widely expressed factors, while TGF-β1 showed the lowest expression.

CONCLUSIONS

Addition of ASC-CM to culture medium enhances follicle survival, development and oestradiol production, and promotes the viability of stromal cells. VEGF, IL-6 and TGF-β1 could be paracrine mediators underlying the beneficial effects.

The role of cellular senescence in ovarian aging

This review explores the relationship between ovarian aging and senescent cell accumulation, as well as the efficacy of senolytics to improve reproductive longevity. Reproductive longevity is determined by the age-associated decline in ovarian reserve, resulting in reduced fertility and eventually menopause. Cellular senescence is a state of permanent cell cycle arrest and resistance to apoptosis. Senescent cells accumulate in several tissues with advancing age, thereby promoting chronic inflammation and age-related diseases. Ovaries also appear to accumulate senescent cells with age, which might contribute to aging of the reproductive system and whole organism through SASP production. Importantly, senolytic drugs can eliminate senescent cells and may present a potential intervention to mitigate ovarian aging. Herein, we review the current literature related to the efficacy of senolytic drugs for extending the reproductive window in mice.

Systemic low-dose anti-fibrotic treatment attenuates ovarian aging in the mouse

The female reproductive system is one of the first to age in humans, resulting in infertility and endocrine disruptions. The aging ovary assumes a fibro-inflammatory milieu which negatively impacts gamete quantity and quality as well as ovulation. Here we tested whether the systemic delivery of anti-inflammatory (Etanercept) or anti-fibrotic (Pirfenidone) drugs attenuates ovarian aging in mice. We first evaluated the ability of these drugs to decrease the expression of fibro-inflammatory genes in primary ovarian stromal cells. Whereas Etanercept did not block Tnf expression in ovarian stromal cells, Pirfenidone significantly reduced Col1a1 expression. We then tested Pirfenidone in vivo where the drug was delivered systemically via mini-osmotic pumps for 6-weeks. Pirfenidone mitigated the age-dependent increase in ovarian fibrosis without impacting overall health parameters. Ovarian function was improved in Pirfenidone-treated mice as evidenced by increased follicle and corpora lutea number, AMH levels, and improved estrous cyclicity. Transcriptomic analysis revealed that Pirfenidone treatment resulted in an upregulation of reproductive function-related genes at 8.5 months and a downregulation of inflammatory genes at 12 months of age. These findings demonstrate that reducing the fibroinflammatory ovarian microenvironment improves ovarian function, thereby supporting modulating the ovarian environment as a therapeutic avenue to extend reproductive longevity.

Single-cell analysis of ovarian myeloid cells identifies aging associated changes in macrophages and signaling dynamics

The aging of mammalian ovary is accompanied by an increase in tissue fibrosis and heightened inflammation. Myeloid cells, including macrophages, monocytes, dendritic cells, and neutrophils, play pivotal roles in shaping the ovarian tissue microenvironment and regulating inflammatory responses. However, a comprehensive understanding of the roles of these cells in the ovarian aging process is lacking. To bridge this knowledge gap, we utilized single-cell RNA sequencing (scRNAseq) and flow cytometry analysis to functionally characterize CD45+ CD11b+ myeloid cell populations in young (3 months old) and aged (14-17 months old) murine ovaries. Our dataset unveiled the presence of five ovarian macrophage subsets, including a Cx3cr1 low Cd81 hi subset unique to the aged murine ovary. Most notably, our data revealed significant alterations in ANNEXIN and TGFβ signaling within aged ovarian myeloid cells, which suggest a novel mechanism contributing to the onset and progression of aging-associated inflammation and fibrosis in the ovarian tissue.

Shear wave elastography to assess stiffness of the human ovary and other reproductive tissues across the reproductive lifespan in health and disease†

The ovary is one of the first organs to show overt signs of aging in the human body, and ovarian aging is associated with a loss of gamete quality and quantity. The age-dependent decline in ovarian function contributes to infertility and an altered endocrine milieu, which has ramifications for overall health. The aging ovarian microenvironment becomes fibro-inflammatory and stiff with age, and this has implications for ovarian physiology and pathology, including follicle growth, gamete quality, ovulation dynamics, and ovarian cancer. Thus, developing a non-invasive tool to measure and monitor the stiffness of the human ovary would represent a major advance for female reproductive health and longevity. Shear wave elastography is a quantitative ultrasound imaging method for evaluation of soft tissue stiffness. Shear wave elastography has been used clinically in assessment of liver fibrosis and characterization of tendinopathies and various neoplasms in thyroid, breast, prostate, and lymph nodes as a non-invasive diagnostic and prognostic tool. In this study, we review the underlying principles of shear wave elastography and its current clinical uses outside the reproductive tract as well as its successful application of shear wave elastography to reproductive tissues, including the uterus and cervix. We also describe an emerging use of this technology in evaluation of human ovarian stiffness via transvaginal ultrasound. Establishing ovarian stiffness as a clinical biomarker of ovarian aging may have implications for predicting the ovarian reserve and outcomes of Assisted Reproductive Technologies as well as for the assessment of the efficacy of emerging therapeutics to extend reproductive longevity. This parameter may also have broad relevance in other conditions where ovarian stiffness and fibrosis may be implicated, such as polycystic ovarian syndrome, late off target effects of chemotherapy and radiation, premature ovarian insufficiency, conditions of differences of sexual development, and ovarian cancer. Summary sentence:  Shear Wave Elastography is a non-invasive technique to study human tissue stiffness, and here we review its clinical applications and implications for reproductive health and disease.

Age-associated increased stiffness of the ovarian microenvironment impairs follicle development and oocyte quality and rapidly alters follicle gene expression

In humans, aging triggers cellular and tissue deterioration, and the female reproductive system is the first to show signs of decline. Reproductive aging is associated with decreased ovarian reserve, decreased quality of the remaining oocytes, and decreased production of the ovarian hormones estrogen and progesterone. With aging, both mouse and human ovaries become pro-fibrotic and stiff. However, whether stiffness directly impairs ovarian function, folliculogenesis, and oocyte quality is unknown. To answer this question, we cultured mouse follicles in alginate gels that mimicked the stiffness of reproductively young and old ovaries. Follicles cultured in stiff hydrogels exhibited decreased survival and growth, decreased granulosa cell viability and estradiol synthesis, and decreased oocyte quality. We also observed a reduction in the number of granulosa cell-oocyte transzonal projections. RNA sequencing revealed early changes in the follicle transcriptome in response to stiffness. Follicles cultured in a stiff environment had lower expression of genes related to follicle development and greater expression of genes related to inflammation and extracellular matrix remodeling than follicles cultured in a soft environment. Altogether, our findings suggest that ovarian stiffness directly modulates folliculogenesis and contributes to the progressive decline in oocyte quantity and quality observed in women of advanced maternal age.

The reduction of the m6A methyltransferase METTL3 in granulosa cells is related to the follicular cysts in pigs

Follicular cysts are a common reproductive disorder in domestic animals that cause considerable economic losses to the farming industry. Effective prevention and treatment methods are lacking because neither the pathogenesis nor formation mechanisms of follicular cysts are well-understood. In this study, we first investigated the granulosa cells (GCs) of cystic follicles isolated from pigs. We observed a significant reduction in the expression of methyltransferase-like 3 (METTL3). Subsequent experiments revealed that METTL3 downregulation in GCs caused a decrease in m6A modification of pri-miR-21. This reduction further inhibited DGCR8 recognition and binding to pri-miR-21, dampening the synthesis of mature miR-21-5p. Additionally, the decrease in miR-21-5p promotes IL-1β expression in GCs. Elevated IL-1β activates the NFκB pathway, in turn upregulating apoptotic genes TNFa and BAX/BCL2. The subsequent apoptosis of GCs and inhibition of autophagy causes downregulation of CYP19A1 expression. These processes lower oestrogen secretion and contribute to follicular cyst formation. In conclusion, our findings provide a foundation for understanding and further exploring the mechanisms of follicular-cyst development in farm animals. This work has important implications for treating ovarian disorders in livestock and could potentially be extended to humans.

Exploring the emerging bidirectional association between inflamm-aging and cellular senescence in organismal aging and disease

There is strong evidence that most individuals in the elderly population are characterized by inflamm-aging which refers to a subtle increase in the systemic pro-inflammatory environment and impaired innate immune activation. Although a variety of distinct factors are associated with the progression of inflamm-aging, emerging research is demonstrating a dynamic relationship between the processes of cellular senescence and inflamm-aging. Cellular senescence is a recognized factor governing organismal aging, and through a characteristic secretome, accumulating senescent cells can induce and augment a pro-inflammatory tissue environment that provides a rationale for immune system-independent activation of inflamm-aging and associated diseases. There is also accumulating evidence that inflamm-aging or its components can directly accelerate the development of senescent cells and ultimately senescent cell burden in tissues in a likely vicious inflammatory loop. The present review is intended to describe the emerging senescence-based molecular etiology of inflamm-aging as well as the dynamic reciprocal interactions between inflamm-aging and cellular senescence. Therapeutic interventions concurrently targeting cellular senescence and inflamm-aging are discussed and limitations as well as research opportunities have been deliberated. An effort has been made to provide a rationale for integrating inflamm-aging with cellular senescence both as an underlying cause and therapeutic target for further studies.

Ovaries of estrogen receptor 1-deficient mice show iron overload and signs of aging

Introduction

Estrogens are crucial regulators of ovarian function, mediating their signaling through binding to estrogen receptors. The disruption of the estrogen receptor 1 (Esr1) provokes infertility associated with a hemorrhagic, cystic phenotype similar to that seen in diseased or aged ovaries. Our previous study indicated the possibility of altered iron metabolism in Esr1-deficient ovaries showing massive expression of lipocalin 2, a regulator of iron homeostasis.

Methods

Therefore, we examined the consequences of depleting Esr1 in mouse ovaries, focusing on iron metabolism. For that reason, we compared ovaries of adult Esr1-deficient animals and age-matched wild type littermates.

Results and discussion

We found increased iron accumulation in Esr1-deficient animals by using laser ablation inductively coupled plasma mass spectrometry. Western blot analysis and RT-qPCR confirmed that iron overload alters iron transport, storage and regulation. In addition, trivalent iron deposits in form of hemosiderin were detected in Esr1-deficient ovarian stroma. The depletion of Esr1 was further associated with an aberrant immune cell landscape characterized by the appearance of macrophage-derived multinucleated giant cells (MNGCs) and increased quantities of macrophages, particularly M2-like macrophages. Similar to reproductively aged animals, MNGCs in Esr1-deficient ovaries were characterized by iron accumulation and strong autofluorescence. Finally, deletion of Esr1 led to a significant increase in ovarian mast cells, involved in iron-mediated foam cell formation. Given that these findings are characteristics of ovarian aging, our data suggest that Esr1 deficiency triggers mechanisms similar to those associated with aging.

Oocyte Aging: A Multifactorial Phenomenon in A Unique Cell

The oocyte is considered to be the largest cell in mammalian species. Women hoping to become pregnant face a ticking biological clock. This is becoming increasingly challenging as an increase in life expectancy is accompanied by the tendency to conceive at older ages. With advancing maternal age, the fertilized egg will exhibit lower quality and developmental competence, which contributes to increased chances of miscarriage due to several causes such as aneuploidy, oxidative stress, epigenetics, or metabolic disorders. In particular, heterochromatin in oocytes and with it, the DNA methylation landscape undergoes changes. Further, obesity is a well-known and ever-increasing global problem as it is associated with several metabolic disorders. More importantly, both obesity and aging negatively affect female reproduction. However, among women, there is immense variability in age-related decline of oocytes' quantity, developmental competence, or quality. Herein, the relevance of obesity and DNA-methylation will be discussed as these aspects have a tremendous effect on female fertility, and it is a topic of continuous and widespread interest that has yet to be fully addressed for the mammalian oocyte.

Chitosan alleviates ovarian aging by enhancing macrophage phagocyte-mediated tissue homeostasis

BACKGROUND

Age-related changes in the ovarian microenvironment are linked to impaired fertility in women. Macrophages play important roles in ovarian tissue homeostasis and immune surveillance. However, the impact of aging on ovarian macrophage function and ovarian homeostasis remains poorly understood.

METHODS

Senescence-associated beta-galactosidase staining, immunohistochemistry, and TUNEL staining were used to assess senescence and apoptosis, respectively. Flow cytometry was employed to evaluate mitochondrial membrane potential (MMP) and apoptosis in granulosa cells lines (KGN), and macrophages phagocytosis. After a 2-month treatment with low molecular weight Chitosan (LMWC), ovarian tissues from mice were collected for comprehensive analysis.

RESULTS

Compared with the liver and uterus, the ovary displayed accelerated aging in an age-dependent manner, which was accompanied by elevated levels of inflammatory factors and apoptotic cells, and impaired macrophage phagocytic activity. The aged KGN cells exhibited elevated reactive oxygen species (ROS) and apoptotic levels alongside decreased MMP. H2O2-induced aging macrophages showed reduced phagocytosis function. Moreover, there were excessive aging macrophages with impaired phagocytosis in the follicular fluid of patients with diminished ovarian reserve (DOR). Notably, LMWC administration alleviated ovarian aging by enhancing macrophage phagocytosis and promoting tissue homeostasis.

CONCLUSIONS

Aging ovarian is characterized by an accumulation of aging and apoptotic granulosa cells, an inflammatory response and macrophage phagocytosis dysfunction. In turn, impaired phagocytosis of macrophage contributes to insufficient clearance of aging and apoptotic granulosa cells and the increased risk of DOR. Additionally, LMWC emerges as a potential therapeutic strategy for age-related ovarian dysfunction.

Single-Cell Atlas of Human Ovaries Reveals The Role Of The Pyroptotic Macrophage in Ovarian Aging

Female fecundity declines in a nonlinear manner with age during the reproductive years, even as ovulatory cycles continue, which reduces female fertility, disrupts metabolic homeostasis, and eventually induces various chronic diseases. Despite this, the aging-related cellular and molecular changes in human ovaries that occur during these reproductive years have not been elucidated. Here, single-cell RNA sequencing (scRNA-seq) of human ovaries is performed from different childbearing ages and reveals that the activation of the pyroptosis pathway increased with age, mainly in macrophages. The enrichment of pyroptotic macrophages leads to a switch from a tissue-resident macrophage (TRM)-involve immunoregulatory microenvironment in young ovaries to a pyroptotic monocyte-derived macrophage (MDM)-involved proinflammatory microenvironment in middle-aged ovaries. This remolded ovarian immuno-microenvironment further promotes stromal cell senescence and accelerated reproductive decline. This hypothesis is validated in a series of cell and animal experiments using GSDMD-KO mice. In conclusion, the work expands the current understanding of the ovarian aging process by illustrating a pyroptotic macrophage-involved immune mechanism, which has important implications for the development of novel strategies to delay senescence and promote reproductive health.

Revitalizing polycystic ovary syndrome: The therapeutic impact of low-dose ∆ tetrahydrocannabinol-9 through reduction of oxidative stress and modulation of macrophage polarization

Objectives

Polycystic ovary syndrome (PCOS) is a complex metabolic and endocrine disorder associated with chronic inflammation. However, the effect of ∆ tetrahydrocannabinol-9 (THC) on PCOS has not been evaluated. Therefore, this study aimed to investigate the immunomodulatory effects of THC in an animal model of PCOS.

Materials and Methods

Twenty female Sprague-Dawley rats, aged 4 weeks, were divided into four groups. The control group received a normal diet, the sham group received a vehicle (carboxymethyl cellulose), the PCOS group received a high-fat diet (HFD) for 16 weeks followed by letrozole for 4 weeks, and the THC group received an HFD for 16 weeks followed by letrozole+THC (0.02 mg/kg) for 4 weeks.

Results

The PCOS animals exhibited significantly higher levels of testosterone, insulin, triglycerides, and total cholesterol, along with elevated inflammatory and oxidative stress markers compared to the control group. Flow cytometry and real-time PCR analysis revealed an increase in M1 macrophage markers and a decrease in M2 macrophage markers compared to the control group. However, the administration of a low dose of THC mitigated these disturbances.

Conclusion

Low-dose THC improved inflammatory responses and shifted the balance of M1/M2 macrophage markers towards M2 macrophages in the animal model of PCOS.

A single-cell atlas of the aging mouse ovary

Ovarian aging leads to diminished fertility, dysregulated endocrine signaling and increased chronic disease burden. These effects begin to emerge long before follicular exhaustion. Female humans experience a sharp decline in fertility around 35 years of age, which corresponds to declines in oocyte quality. Despite a growing body of work, the field lacks a comprehensive cellular map of the transcriptomic changes in the aging mouse ovary to identify early drivers of ovarian decline. To fill this gap we performed single-cell RNA sequencing on ovarian tissue from young (3-month-old) and reproductively aged (9-month-old) mice. Our analysis revealed a doubling of immune cells in the aged ovary, with lymphocyte proportions increasing the most, which was confirmed by flow cytometry. We also found an age-related downregulation of collagenase pathways in stromal fibroblasts, which corresponds to rises in ovarian fibrosis. Follicular cells displayed stress-response, immunogenic and fibrotic signaling pathway inductions with aging. This report provides critical insights into mechanisms responsible for ovarian aging phenotypes. The data can be explored interactively via a Shiny-based web application.

Chronic low-grade inflammation and ovarian dysfunction in women with polycystic ovarian syndrome, endometriosis, and aging

The ovarian microenvironment is critical for follicular development and oocyte maturation. Maternal conditions, including polycystic ovary syndrome (PCOS), endometriosis, and aging, may compromise the ovarian microenvironment, follicular development, and oocyte quality. Chronic low-grade inflammation can induce oxidative stress and tissue fibrosis in the ovary. In PCOS, endometriosis, and aging, pro-inflammatory cytokine levels are often elevated in follicular fluids. In women with obesity and PCOS, hyperandrogenemia and insulin resistance induce ovarian chronic low-grade inflammation, thereby disrupting follicular development by increasing oxidative stress. In endometriosis, ovarian endometrioma-derived iron overload can induce chronic inflammation and oxidative stress, leading to ovarian ferroptosis and fibrosis. In inflammatory aging (inflammaging), senescent cells may secrete senescence-associated secretory phenotype factors, causing chronic inflammation and oxidative stress in the ovary. Therefore, controlling chronic low-grade inflammation and fibrosis in the ovary would present a novel therapeutic strategy for improving the follicular microenvironment and minimizing ovarian dysfunction.

The stromal microenvironment and ovarian aging: mechanisms and therapeutic opportunities

For decades, most studies of ovarian aging have focused on its functional units, known as follicles, which include oocytes and granulosa cells. However, in the ovarian stroma, there are a variety of somatic components that bridge the gap between general aging and ovarian senescence. Physiologically, general cell types, microvascular structures, extracellular matrix, and intercellular molecules affect folliculogenesis and corpus luteum physiology alongside the ovarian cycle. As a result of damage caused by age-related metabolite accumulation and external insults, the microenvironment of stromal cells is progressively remodeled, thus inevitably perturbing ovarian physiology. With the established platforms for follicle cryopreservation and in vitro maturation and the development of organoid research, it is desirable to develop strategies to improve the microenvironment of the follicle by targeting the perifollicular environment. In this review, we summarize the role of stromal components in ovarian aging, describing their age-related alterations and associated effects. Moreover, we list some potential techniques that may mitigate ovarian aging based on their effect on the stromal microenvironment.

Impact of NAD+ metabolism on ovarian aging

Nicotinamide adenine dinucleotide (NAD+), a crucial coenzyme in cellular redox reactions, is closely associated with age-related functional degeneration and metabolic diseases. NAD exerts direct and indirect influences on many crucial cellular functions, including metabolic pathways, DNA repair, chromatin remodeling, cellular senescence, and immune cell functionality. These cellular processes and functions are essential for maintaining tissue and metabolic homeostasis, as well as healthy aging. Causality has been elucidated between a decline in NAD levels and multiple age-related diseases, which has been confirmed by various strategies aimed at increasing NAD levels in the preclinical setting. Ovarian aging is recognized as a natural process characterized by a decline in follicle number and function, resulting in decreased estrogen production and menopause. In this regard, it is necessary to address the many factors involved in this complicated procedure, which could improve fertility in women of advanced maternal age. Concerning the decrease in NAD+ levels as ovarian aging progresses, promising and exciting results are presented for strategies using NAD+ precursors to promote NAD+ biosynthesis, which could substantially improve oocyte quality and alleviate ovarian aging. Hence, to acquire further insights into NAD+ metabolism and biology, this review aims to probe the factors affecting ovarian aging, the characteristics of NAD+ precursors, and the current research status of NAD+ supplementation in ovarian aging. Specifically, by gaining a comprehensive understanding of these aspects, we are optimistic about the prominent progress that will be made in both research and therapy related to ovarian aging.

New insight into the role of macrophages in ovarian function and ovarian aging

Macrophages (MΦs) are the most abundant leukocytes in mammalian ovaries that have heterogeneity and plasticity. A body of evidence has indicated that these cells are important in maintaining ovarian homeostasis and they play critical roles in ovarian physiological events, such as folliculogenesis, ovulation, corpus luteum formation and regression. As females age, ovarian tissue microenvironment is typified by chronic inflammation with exacerbated ovarian fibrosis. In response to specific danger signals within aged ovaries, macrophages polarize into different M1 or M2 phenotypes, and specialize in unique functions to participate in the ovarian aging process. In this review, we will focus on the physiologic roles of MΦs in normal ovarian functions. Furthermore, we will discuss the roles of MΦs in the process of ovarian senescence, as well as the novel techniques applied in this field.

Proteomic quantification of native and ECM-enriched mouse ovaries reveals an age-dependent fibro-inflammatory signature

The ovarian microenvironment becomes fibrotic and stiff with age, in part due to increased collagen and decreased hyaluronan. However, the extracellular matrix (ECM) is a complex network of hundreds of proteins, glycoproteins, and glycans which are highly tissue specific and undergo pronounced changes with age. To obtain an unbiased and comprehensive profile of age-associated alterations to the murine ovarian proteome and ECM, we used a label-free quantitative proteomic methodology. We validated conditions to enrich for the ECM prior to proteomic analysis. Following analysis by data-independent acquisition (DIA) and quantitative data processing, we observed that both native and ECM-enriched ovaries clustered separately based on age, indicating distinct age-dependent proteomic signatures. We identified a total of 4,721 proteins from both native and ECM-enriched ovaries, of which 383 proteins were significantly altered with advanced age, including 58 ECM proteins. Several ECM proteins upregulated with age have been associated with fibrosis in other organs, but to date their roles in ovarian fibrosis are unknown. Pathways regulating DNA metabolism and translation were downregulated with age, whereas pathways involved in ECM remodeling and immune response were upregulated. Interestingly, immune-related pathways were upregulated with age even in ECM-enriched ovaries, suggesting a novel interplay between the ECM and the immune system. Moreover, we identified putative markers of unique immune cell populations present in the ovary with age. These findings provide evidence from a proteomic perspective that the aging ovary provides a fibroinflammatory milieu, and our study suggests target proteins which may drive these age-associated phenotypes for future investigation.

CD38 regulates ovarian function and fecundity via NAD+ metabolism

Mammalian female reproductive lifespan is typically significantly shorter than life expectancy and is associated with a decrease in ovarian NAD+ levels. However, the mechanisms underlying this loss of ovarian NAD+ are unclear. Here, we show that CD38, an NAD+ consuming enzyme, is expressed in the ovarian extrafollicular space, primarily in immune cells, and its levels increase with reproductive age. Reproductively young mice lacking CD38 exhibit larger primordial follicle pools, elevated ovarian NAD+ levels, and increased fecundity relative to wild type controls. This larger ovarian reserve results from a prolonged window of follicle formation during early development. However, the beneficial effect of CD38 loss on reproductive function is not maintained at advanced age. Our results demonstrate a novel role of CD38 in regulating ovarian NAD+ metabolism and establishing the ovarian reserve, a critical process that dictates a female's reproductive lifespan.

Spatial Transcriptomics of Aging Rat Ovaries Reveals Unexplored Cell Subpopulations with Reduced Antioxidative Defense

INTRODUCTION

Ovarian aging is characterized by a gradual decline in quantity and quality of oocytes and lower chance of fertility. Better understanding the genetic modulation during ovarian aging can further address available treatment options for aging-related ovarian diseases and fertility preservation.

METHODS

A novel technique spatial transcriptomics (ST) was used to investigate the spatial transcriptome features of rat ovaries. Transcriptomes from ST spots in the young and aged ovaries were clustered using differentially expressed genes. These data were analyzed to determine the spatial organization of age-induced heterogeneity and potential mechanisms underlying ovarian aging.

RESULTS

In this study, ST technology was applied to profile the comprehensive spatial imaging in young and aged rat ovary. Fifteen ovarian cell clusters with distinct gene-expression signatures were identified. The gene expression dynamics of granulosa cell clusters revealed three sub-types with sequential developmental stages. Aged ovary showed a significant decrease in the number of granulosa cells from the antral follicle. Besides, a remarkable rearrangement of interstitial gland cells was detected in aging ovary. Further analysis of aging-associated transcriptional changes revealed that the disturbance of oxidative pathway was a crucial factor in ovarian aging.

CONCLUSIONS

This study firstly described an aging-related spatial transcriptome changes in ovary and identified the potential targets for prevention of ovarian aging. These data may provide the basis for further investigations of the diagnosis and treatment of aging-related ovarian disorders.

A single-cell atlas of the aging murine ovary

Ovarian aging leads to diminished fertility, dysregulated endocrine signaling, and increased chronic disease burden. These effects begin to emerge long before follicular exhaustion. Around 35 years old, women experience a sharp decline in fertility, corresponding to declines in oocyte quality. Despite a growing body of work, the field lacks a comprehensive cellular map of the transcriptomic changes in the aging ovary to identify early drivers of ovarian decline. To fill this gap, we performed single-cell RNA sequencing on ovarian tissue from young (3-month-old) and reproductively aged (9-month-old) mice. Our analysis revealed a doubling of immune cells in the aged ovary, with lymphocyte proportions increasing the most, which was confirmed by flow cytometry. We also found an age-related downregulation of collagenase pathways in stromal fibroblasts, which corresponds to rises in ovarian fibrosis. Follicular cells displayed stress response, immunogenic, and fibrotic signaling pathway inductions with aging. This report raises provides critical insights into mechanisms responsible for ovarian aging phenotypes.

Presence of ovarian stromal aberrations after cessation of testosterone therapy in a transgender mouse model†

Some transmasculine individuals may be interested in pausing gender-affirming testosterone therapy and carrying a pregnancy. The ovarian impact of taking and pausing testosterone is not completely understood. The objective of this study was to utilize a mouse model mimicking transmasculine testosterone therapy to characterize the ovarian dynamics following testosterone cessation. We injected postpubertal 9-10-week-old female C57BL/6N mice once weekly with 0.9 mg of testosterone enanthate or a vehicle control for 6 weeks. All testosterone-treated mice stopped cycling and demonstrated persistent diestrus within 1 week of starting testosterone, while control mice cycled regularly. After 6 weeks of testosterone therapy, one group of testosterone-treated mice and age-matched vehicle-treated diestrus controls were sacrificed. Another group of testosterone-treated mice were maintained after stopping testosterone therapy and were sacrificed in diestrus four cycles after the resumption of cyclicity along with age-matched vehicle-treated controls. Ovarian histological analysis revealed stromal changes with clusters of large round cells in the post testosterone group as compared to both age-matched controls and mice at 6 weeks on testosterone. These clusters exhibited periodic acid-Schiff staining, which has been previously reported in multinucleated macrophages in aging mouse ovaries. Notably, many of these cells also demonstrated positive staining for macrophage markers CD68 and CD11b. Ovarian ribonucleic acid-sequencing found upregulation of immune pathways post testosterone as compared to age-matched controls and ovaries at 6 weeks on testosterone. Although functional significance remains unknown, further attention to the ovarian stroma may be relevant for transmasculine people interested in pausing testosterone to carry a pregnancy.

Chito-oligosaccharides and macrophages have synergistic effects on improving ovarian stem cells function by regulating inflammatory factors

BACKGROUND

Chronic low-grade inflammation and ovarian germline stem cells (OGSCs) aging are important reasons for the decline of ovarian reserve function, resulting in ovarian aging and infertility. Regulation of chronic inflammation is expected to promote the proliferation and differentiation of OGSCs, which will become a key means for maintaining and remodeling ovarian function. Our previous study demonstrated that Chitosan Oligosaccharides (Cos) promoted the OGSCs proliferation and remodelled the ovarian function through improving the secretion of immune related factors,but the mechanism remains unclear, and the role of macrophages, the important source of various inflammatory mediators in the ovary needs to be further studied. In this study, we used the method of macrophages and OGSCs co-culture to observe the effect and mechanism of Cos on OGSCs, and explore what contribution macrophages give during this process. Our finding provides new drug treatment options and methods for the prevention and treatment of premature ovarian failure and infertility.

METHODS

We used the method of macrophages and OGSCs co-culture to observe the effect and mechanism of Cos on OGSCs, and explore the important contribution of macrophages in it. The immunohistochemical staining was used to locate the OGSCs in the mouse ovary. Immunofluorescent staining, RT-qPCR and ALP staining were used to identify the OGSCs. CCK-8 and western blot were used to evaluate the OGSCs proliferation. β-galactosidase(SA-β-Gal) staining and western blot were used to detect the changing of cyclin-dependent kinase inhibitor 1A(P21), P53, Recombinant Sirtuin 1(SIRT1) and Recombinant Sirtuin 3(SIRT3). The levels of immune factors IL-2, IL-10, TNF-α and TGF-β were explored by using Western blot and ELISA.

RESULTS

We found that Cos promoted OGSCs proliferation in a dose-and time-dependent manner, accompanied by IL-2, TNF-α increase and IL-10, TGF-β decrease. Mouse monocyte-macrophages Leukemia cells(RAW) can also produce the same effect as Cos. When combined with Cos, it can enhance the proliferative effect of Cos in OGSCs, and further increase IL-2, TNF-α and further decrease IL-10, TGF-β. The macrophages can enhance the proliferative effect of Cos in OGSCs is also associated with the further increase in IL-2, TNF-α and the further decrease in IL-10, TGF-β. In this study, we determined that the anti-aging genes SIRT-1 and SIRT-3 protein levels were increased by Cos and RAW respectively, whereas the senescence-associated SA-β-Gal and aging genes P21 and P53 were decreased. Cos and RAW had a protective effect on OGSCs delaying aging. Furthermore, RAW can further decrease the SA-β-Gal and aging genes P21 and P53 by Cos, and further increase SIRT1 and SIRT3 protein levels in OGSCs by Cos.

CONCLUSION

In conclusion, Cos and macrophages have synergistic effects on improving OGSCs function and delaying ovarian aging by regulating inflammatory factors.

Multi-omics analysis of the Indian ovarian cancer cohort revealed histotype-specific mutation and gene expression patterns

Introduction: In India, OVCa is women’s third most common and lethal cancer type, accounting for 6.7% of observed cancer incidences. The contribution of somatic mutations, aberrant expression of gene and splice forms in determining the cell fate, gene networks, tumour-specific variants, and the role of immune fraction infiltration have been proven essential in understanding tumorigenesis. However, their interplay in OVCa in a histotype-specific manner remains unclear in the Indian context. In the present study, we aimed to unravel the Indian population histotype-specific exome variants, differentially expressed gene modules, splice events and immune profiles of OVCa samples.

Methods: We analysed 10 tumour samples across 4 ovarian cancer histotypes along with 2 normal patient samples. This included BCFtool utilities and CNVkit for exome, WGCNA and DESeq2 for obtaining differential module hub genes and dysregulated miRNA targets, CIBERSORTx for individual immune profiles and rMATS for tumour specific splice variants.

Result: We identified population-specific novel mutations in Cancer Gene Census Tier1 and Tier2 genes. MUC16, MUC4, CIITA, and NCOR2 were among the most mutated genes, along with TP53. Transcriptome analysis showed significant overexpression of mutated genes MUC16, MUC4, and CIITA, whereas NCOR2 was downregulated. WGCNA revealed histotype-specific gene hubs and networks. Among the significant pathways, alteration in the immune system was one of the pathways, and immune profiling using CIBERSORTx revealed histotype-specific immune cell fraction. miRNA analysis revealed miR-200 family, miR-200a and miR-429 were upregulated in HGSOCs.Splice factor abrasion caused splicing perturbations, with the most abundant alternative splice event being exon skipping and the most spliced gene, SNHG17. Pathway analysis of spliced genes revealed translational elongation and Base excision repair as the pathways altered in OVCa.

Conclusion: Integrated exome, transcriptome, and splicing patterns revealed different population-specific molecular signatures of ovarian cancer histotypes in the Indian Cohort.

Role of Inflammaging on the Reproductive Function and Pregnancy

During female lifetime and pregnancy, inflammation and cellular senescence are implicated in physiological processes, from ovulation and menstruation, to placental homeostasis and delivery. Several lifestyles, nutritional, and environmental insults, as well as long-lasting pregestational inflammatory diseases may lead to detrimental effects in promoting and sustaining a chronic excessive inflammatory response and inflammaging, which finally contribute to the decay of fertility and pregnancy outcome, with a negative effect on placental function, fetal development, and future health risk profile in the offspring. Maladaptation to pregnancy and obstetric disease may in turn increase maternal inflammaging in a feedback loop, speeding up aging processes and outbreak of chronic diseases. Maternal inflammaging may also impact, through transgenerational effects, on future adult health. Hence, efficacious interventions should be implemented by physicians and healthcare professionals involved in prevention activities to reduce the modifiable factors contributing to the inflammaging process in order to improve public health.

Aging-Related Ovarian Failure and Infertility: Melatonin to the Rescue

Aging has a major detrimental effect on the optimal function of the ovary with changes in this organ preceding the age-related deterioration in other tissues, with the middle-aged shutdown leading to infertility. Reduced fertility and consequent inability to conceive by women in present-day societies who choose to have children later in life leads to increased frustration. Melatonin is known to have anti-aging properties related to its antioxidant and anti-inflammatory actions. Its higher follicular fluid levels relative to blood concentrations and its likely synthesis in the oocyte, granulosa, and luteal cells suggest that it is optimally positioned to interfere with age-associated deterioration of the ovary. Additionally, the end of the female reproductive span coincides with a significant reduction in endogenous melatonin levels. Thus, the aims are to review the literature indicating melatonin production in mitochondria of oocytes, granulosa cells, and luteal cells, identify the multiple processes underlying changes in the ovary, especially late in the cessation of the reproductive life span, summarize the physiological and molecular actions of melatonin in the maintenance of normal ovaries and in the aging ovaries, and integrate the acquired information into an explanation for considering melatonin in the treatment of age-related infertility. Use of supplemental melatonin may help preserve fertility later in life and alleviate frustration in women delaying childbearing age, reduce the necessity of in vitro fertilization–embryo transfer (IVF-ET) procedures, and help solve the progressively increasing problem of non-aging-related infertility in women throughout their reproductive life span. While additional research is needed to fully understand the effects of melatonin supplementation on potentially enhancing fertility, studies published to date suggest it may be a promising option for those struggling with infertility.

Antimüllerian hormone is not associated with embryo ploidy in patients with and without infertility undergoing in vitro fertilization with preimplantation genetic testing

OBJECTIVE

To assess the association between antimüllerian hormone (AMH) and embryo ploidy rates in 2 cohorts of patients undergoing in vitro fertilization (IVF) with trophectoderm biopsy for preimplantation genetic testing for aneuploidy (PGT-A): the general population of women pursuing IVF with PGT-A (Infertile cohort) and women pursuing IVF with preimplantation genetic testing for monogenic disorders (PGT-M) owing to the risk of hereditary monogenic diseases (Non-infertile cohort).

DESIGN

Retrospective cohort study.

SETTING

Academic center.

PATIENT(S)

Patients undergoing their first cycle of IVF with trophectoderm biopsy and PGT-A or PGT-A and PGT-M in our center between March 2012 and June 2020. Patients of advanced maternal age according to the Bologna criteria (age ≥40 years) and patients who underwent fresh embryo transfers were excluded.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Proportion of euploid, mosaic, and aneuploid embryos per cycle.

RESULT(S)

"Infertile" (n = 926) and "Non-infertile" (n = 214) patients were stratified on the basis of AMH levels, with low-AMH defined as <1.1 ng/mL in accordance with the Bologna criteria. Age-adjusted regression models showed no relationship between AMH classification and proportion of euploid, mosaic, and aneuploid embryos in the Infertile or Non-infertile cohorts. In the Infertile cohort, no association between AMH classification and embryo ploidy rates was identified in a subgroup analysis of patients aged <35 years, 35-37 years, and 38-39 years. These findings persisted in a sensitivity analysis of infertile patients stratified into AMH (ng/mL) quartile categories.

CONCLUSION(S)

No association was found between AMH and the proportion of euploid, mosaic, or aneuploid embryos in 2 large cohorts of patients undergoing IVF with PGT-A (Infertile patients) or PGT-A and PGT-M (Non-infertile patients), suggesting that a quantitative depletion of ovarian reserve does not predict the ploidy status of the embryo cohort.

Two distinct resident macrophage populations coexist in the ovary

Introduction

Tissue-resident macrophages (TRMs) are highly heterogeneous and have a complex and important role in tissue support, homeostasis, and function. The heterogeneity, maintenance, and function of TRMs, as one of the major immune cells in the ovary, are not well understood.

Methods

Application of flow cytometry, Parabiosis, Fate mapping, Macrophage depletion, etc.

Results

Here, we described two distinct macrophage subsets, F4/80^hiCD11b^int and F4/80^intCD11b^hi, with different phenotypic characteristics in the ovary of mice. The F4/80^hiCD11b^int population contained a distinct CD206⁺ subgroup and highly expressed CD81, while the F4/80^intCD11b^hi subset showed higher expression of CCR2 and TLR2. Notably, Ly6c⁺ macrophages were present almost exclusively in the F4/80^intCD11b^hi subpopulation. Combining in vivo fate mapping and parabiotic mouse models, we characterized the longevity and replenishment of the two macrophage populations. We found that both the F4/80^hiCD11b^int and F4/80^intCD11b^hi subsets were ovary-resident. Importantly, the F4/80^hiCD11b^int macrophages acted as a self-maintaining and long-lived population with a modest monocyte contribution at a steady state, and the F4/80^intCD11b^hi subpopulation had a relatively short lifespan with a greater contribution from monocytes. After macrophage ablation, disturbance of estradiol secretion and ovarian hemorrhage due to damaged vascular integrity was observed in mice.

Discussion

Our data provide critical insights into ovarian macrophage heterogeneity and highlight the strategic role of TRMs in ovarian homeostasis and physiology.

Squeezing the eggs to grow: The mechanobiology of mammalian folliculogenesis

The formation of functional eggs (oocyte) in ovarian follicles is arguably one of the most important events in early mammalian development since the oocytes provide the bulk genetic and cytoplasmic materials for successful reproduction. While past studies have identified many genes that are critical to normal ovarian development and function, recent studies have highlighted the role of mechanical force in shaping folliculogenesis. In this review, we discuss the underlying mechanobiological principles and the force-generating cellular structures and extracellular matrix that control the various stages of follicle development. We also highlight emerging techniques that allow for the quantification of mechanical interactions and follicular dynamics during development, and propose new directions for future studies in the field. We hope this review will provide a timely and useful framework for future understanding of mechano-signalling pathways in reproductive biology and diseases.

Single-cell profiling of mouse and primate ovaries identifies high levels of EGFR for stromal cells in ovarian aging

Increased ovarian fibrosis and an expanded stromal cell compartment are the main characteristics of aging ovaries. However, the molecular mechanisms and the key factor of stromal cells underlying ovarian aging remain unclear. Here, we explored single-cell transcriptomic data of ovaries from the adult mouse (4,363 cells), young (1,122 cells), and aged (1,479 cells) non-human primates (NHPs) to identify expression patterns of stromal cells between young and old ovaries. An increased number of stromal cells (p = 0.0386) was observed in aged ovaries of NHPs, with enrichment processes related to the collagen-containing extracellular matrix. In addition, differentially expressed genes of stromal cells between young and old ovaries were regulated by ESR1 (p = 7.94E-08) and AR (p = 1.99E-05). Among them, EGFR was identified as the common target and was highly expressed (p = 7.69E-39) in old ovaries. In human ovaries, the correlated genes of EGFR were associated with the process of the cell-substrate junction. Silencing of EGFR in human ovarian stromal cells led to the reduction of cell-substrate junction via regulating phosphorylation modification of the AKT-mTOR signaling pathway and stromal cell marker genes. Overall, we identified high levels of EGFR for stromal cells in ovarian aging, which provides insight into the cell type-specific molecular mechanisms underlying ovarian aging at single-cell resolution.

Fecal microbiota transplantation from young donor mice improves ovarian function in aged mice

Advanced maternal age is characterized by declines in the quantity and quality of oocytes in the ovaries, and the aging process is accompanied by changes in gut microbiota composition. However, little is known about the relationship between gut microbiota and ovarian aging. By using fecal microbiota transplantation (FMT) to transplant material from young (5-week-old) into aged (42-week-old) mice, we find that the composition of gut microbiota in FMT-treated mice presents a "younger-like phenotype" and an increase of commensal bacteria, such as Bifidobacterium and Ruminococcaceae. Moreover, the FMT-treated mice show increased anti-inflammatory cytokine IL-4 and decreased pro-inflammatory cytokine IFN-γ. Fertility tests for assessing ovarian function reveal that the first litter size of female FMT-treated mice is significantly higher than that of the non-FMT group. Morphology analysis demonstrates a dramatic decrease in follicle atresia and apoptosis as well as an increase in cellular proliferation in the ovaries of the FMT-treated mice. Our results also show that FMT improves the immune microenvironment in aged ovaries, with decreased macrophages and macrophage-derived multinucleated giant cells (MNGCs). These results suggest that FMT from young donors could be a good choice for delaying ovarian aging.