GlmS plays a key role in the virulence factor expression and biofilm formation ability of Staphylococcus aureus promoted by advanced glycation end products

Staphylococcus aureus (S. aureus) is well known for its biofilm formation ability and is responsible for serious, chronic refractory infections worldwide. We previously demonstrated that advanced glycation end products (AGEs), a hallmark of chronic hyperglycaemia in diabetic tissues, enhanced biofilm formation by promoting eDNA release via sigB upregulation in S. aureus, contributing to the high morbidity and mortality of patients presenting a diabetic foot ulcer infection. However, the exact regulatory network has not been completely described. Here, we used pull-down assay and LC-MS/MS to identify the GlmS as a candidate regulator of sigB in S. aureus stimulated by AGEs. Dual-luciferase assays and electrophoretic mobility shift assays (EMSAs) revealed that GlmS directly upregulated the transcriptional activity of sigB. We constructed NCTC 8325 ∆glmS for further validation. qRT-PCR analysis revealed that AGEs promoted both glmS and sigB expression in the NCTC 8325 strain but had no effect on NCTC 8325 ∆glmS. NCTC 8325 ∆glmS showed a significant attenuation in biofilm formation and virulence factor expression, accompanied by a decrease in sigB expression, even under AGE stimulation. All of the changes, including pigment deficiency, decreased haemolysis ability, downregulation of hla and hld expression, and less and sparser biofilms, indicated that sigB and biofilm formation ability no longer responded to AGEs in NCTC 8325 ∆glmS. Our data extend the understanding of GlmS in the global regulatory network of S. aureus and demonstrate a new mechanism by which AGEs can upregulate GlmS, which directly regulates sigB and plays a significant role in mediating biofilm formation and virulence factor expression.

The role of vitamin D3 in follicle development

Vitamin D3 plays a crucial role in female reproduction. As research progresses, the mechanisms of action of vitamin D3 on follicular development have been widely discussed. Firstly, key enzymes involved in the synthesis and metabolism of vitamin D3 have been discovered in the ovary, suggesting that vitamin D3 can be synthesized and metabolized locally within the ovary. Additionally, the detection of vitamin D3 receptors (VDR) in follicles suggests that vitamin D3 may exert its effects by binding specifically to these receptors during follicular development. Further research indicates that vitamin D3 promotes follicular growth by enhancing the development of granulosa cells (GCs) and oocytes. Currently, the mechanism of action of vitamin D3 in follicular development is becoming increasingly clear. Vitamin D3 promotes oocyte development by regulating molecules involved in meiotic arrest in oocytes. It also enhances granulosa cell proliferation by stimulating steroid hormone synthesis and cell cycle regulation. Additionally, vitamin D3 exerts anti-inflammatory effects by reducing oxidative stress and advanced glycation end-products (AGEs), mitigating the detrimental effects of inflammation on follicular development. These functions of vitamin D3 have clinical applications, such as in treating polycystic ovary syndrome (PCOS), improving female fertility, and enhancing outcomes in in vitro fertilization (IVF). This review summarizes the research progress on the role and mechanisms of vitamin D3 in follicular development and briefly summarizes its clinical applications.

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.

FSHR-mTOR-HIF1 signaling alleviates mouse follicles from AMPK-induced atresia

The majority of activated ovarian follicles undergo atresia during reproductive life in mammals, and only a small number of follicles are ovulated. Though hormone treatment has been widely used to promote folliculogenesis, the molecular mechanism behind follicle selection and atresia remains under debate due to inconsistency among investigation models. Using a high-throughput molecular pathology strategy, we depicted a transcriptional atlas of mouse follicular granulosa cells (GCs) under physiological condition and obtained molecular signatures in healthy and atresia GCs during development. Functional results revealed hypoxia-inducible factor 1 (HIF1) as a major effector downstream of follicle-stimulating hormone (FSH), and HIF1 activation is essential for follicle growth. Energy shortage leads to prevalent AMP-activated protein kinase (AMPK) activation and drives follicular atresia. FSHR-mTOR-HIF1 signaling helps follicles escape from the atresia fate, while energy stress persists. Our work provides a comprehensive understanding of the molecular network behind follicle selection and atresia under physiological condition.

Pyridoxamine protects human granulosa cells against advanced glycation end-products-induced steroidogenesis disturbances

BACKGROUND

Ovarian advanced glycation end-products (AGEs) accumulation is associated with ovarian granulosa cells (GCs) dysfunction. Vitamin B6 derivatives positively affected reproduction. The current study was conducted to elucidate the AGEs effects on human luteinized mural GCs steroidogenesis in the presence or absence of pyridoxamine (PM).

METHODS AND RESULTS

Isolated GCs of 50 healthy women were divided into four parts and treated with media alone (Control), PM alone, or human glycated albumin (HGA) with/without PM. Main steroidogenic enzymes and hormones were assessed by qRT-PCR and ELISA. The AGE receptor (RAGE) protein was also determined using Western blotting. The non-toxic concentration of HGA increased the expression of RAGE, StAR, 3β-HSD, and 17β-HSD (P < 0.0001 for all) but decreased the expression of CYP19A1 at mRNA levels. The increased RAGE protein expression was also confirmed by western blot analysis. These effects resulted in declined estradiol (E2), slightly, and a sharp rise in progesterone (P4) and testosterone (T) levels, respectively. PM, on its own, ameliorated the HGA-altered enzyme expression and, thereby, corrected the aberrant levels of E2, P4, and T. These effects are likely mediated by regulating the RAGE gene and protein expression.

CONCLUSION

This study indicates that hormonal dysfunctions induced by the AGEs-RAGE axis in luteinized GCs are likely rectified by PM treatment. This effect is likely acquired by reduced expression of RAGE. A better understanding of how AGEs and PM interact in ovarian physiology and pathology may lead to more targeted therapy for treating ovarian dysfunction.

Follicular fluid advanced glycation end products in assisted reproduction: A systematic review

Follicular fluid (FF) advanced glycation end products (AGEs) have been associated with low oocyte quality and number, low fertilization rate, impaired embryonic development and low pregnancy rate. These findings are especially relevant in women undergoing in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI), ie, assisted reproductive technology (ART). A systematic literature search was conducted to examine various AGEs including pentosidine, carboxymethyl-lysine (CML), methylglyoxal 5-hydro-5-methylimidazolones (MG-H1), toxic AGE (TAGE), and soluble receptor for AGE (sRAGE) with ART outcomes. Studies showed that total AGEs and sRAGE in FF were associated with the ovarian response, follicle number, retrieved oocyte number, mature (MII) oocyte number, fertilization rate, embryo number, embryo quality, and successful pregnancy. Although FF AGEs could be considered predictive biomarkers, population heterogeneity and differences in ovulation induction protocols make the findings less clear. This review highlights important role of AGEs in ART and necessity of evaluating AGEs in serum vs with FF to better predict ART outcomes.

Biomarkers of aging

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

Genetic Polymorphisms in the 3'-Untranslated Regions of SMAD5, FN3KRP, and RUNX-1 Are Associated with Recurrent Pregnancy Loss

Recurrent pregnancy loss (RPL) is typically defined as two or more consecutive pregnancy losses prior to 20 weeks of gestation. Although the causes of idiopathic RPL are not completely understood, vascular development and glucose concentration were reported to correlate with the pregnancy loss. The TGF-β signaling pathway which plays a significant role in pregnancy is activated by the interaction between high glucose and SMAD signaling and affects the vascular cells. SMAD5 and RUNX-1 are involved in the TGF-β signaling pathway and contribute to advanced glycation end products (AGEs) production and vascular development. FN3KRP, a newly described gene, is also associated with vascular diseases and suggested to relate to AGEs. Therefore, in the present study, we investigated associations between RPL risk and genetic polymorphisms of SMAD5, FN3KRP, and RUNX-1 in 388 women with RPL and 280 healthy control women of Korean ethnicity. Participants were genotyped using real-time polymerase chain reaction and restriction fragment length polymorphism assay to determine the frequency of SMAD5 rs10515478 C>G, FN3KRP rs1046875 G>A, and RUNX-1 rs15285 G>A polymorphisms. We found that women with RPL had lower likelihoods of the FN3KRP rs1046875 AA genotype (adjusted odds ratio (AOR), 0.553; p = 0.010) and recessive model (AOR, 0.631; p = 0.017). Furthermore, combination analysis showed that SMAD5 rs10515478 C>G and FN3KRP rs1046875 G>A mutant alleles were together associated with reduced RPL risk. These findings suggest that the FN3KRP rs1046875 G>A polymorphism has a significant role on the prevalence of RPL in Korean women. Considering that it is the first study indicating a significant association between FN3KRP and pregnancy disease, RPL, our results suggest the need for further investigation of the role of FN3KRP in pregnancy loss.

Age-associated changes in cumulus cells and follicular fluid: the local oocyte microenvironment as a determinant of gamete quality

The ovary is the first organ to age in humans with functional decline evident already in women in their early 30s. Reproductive aging is characterized by a decrease in oocyte quantity and quality, which is associated with an increase in infertility, spontaneous abortions, and birth defects. Reproductive aging also has implications for overall health due to decreased endocrinological output. Understanding the mechanisms underlying reproductive aging has significant societal implications as women globally are delaying childbearing and medical interventions have greatly increased the interval between menopause and total lifespan. Age-related changes inherent to the female gamete are well-characterized and include defects in chromosome and mitochondria structure, function, and regulation. More recently, it has been appreciated that the extra-follicular ovarian environment may have important direct or indirect impacts on the developing gamete, and age-dependent changes include increased fibrosis, inflammation, stiffness, and oxidative damage. The cumulus cells and follicular fluid that directly surround the oocyte during its final growth phase within the antral follicle represent additional critical local microenvironments. Here we systematically review the literature and evaluate the studies that investigated the age-related changes in cumulus cells and follicular fluid. Our findings demonstrate unique genetic, epigenetic, transcriptomic, and proteomic changes with associated metabolomic alterations, redox status imbalance, and increased apoptosis in the local oocyte microenvironment. We propose a model of how these changes interact, which may explain the rapid decline in gamete quality with age. We also review the limitations of published studies and highlight future research frontiers.

Aging conundrum: A perspective for ovarian aging

Progressive loss of physiological integrity and accumulation of degenerative changes leading to functional impairment and increased susceptibility to diseases are the main features of aging. The ovary, the key organ that maintains female reproductive and endocrine function, enters aging earlier and faster than other organs and has attracted extensive attention from society. Ovarian aging is mainly characterized by the progressive decline in the number and quality of oocytes, the regulatory mechanisms of which have yet to be systematically elucidated. This review discusses the hallmarks of aging to further highlight the main characteristics of ovarian aging and attempt to explore its clinical symptoms and underlying mechanisms. Finally, the intervention strategies related to aging are elaborated, especially the potential role of stem cells and cryopreservation of embryos, oocytes, or ovarian tissue in the delay of ovarian aging.

Network Pharmacology-Based Strategy for Predicting Active Ingredients and Potential Targets of Coptis chinensis Franchin Polycystic Ovary Syndrome

Background

Polycystic ovary syndrome (PCOS) causes low fertility in females. Coptis chinensis (C. chinensis) is used to clear heat and dampness, purify fire, and detoxify in traditional Chinese medicine (TCM). Although C. chinensis has demonstrated efficacy against PCOS in clinical practice, there are no available data regarding the bioactive components of C. chinensis, their targets, and molecular mechanisms underlying their effects.

Methods and Results

Network pharmacology was used to analyze the bioactive components of C. chinensis, their targets, and signaling pathways underlying their effects. The TCM systems pharmacology database and analysis platform (TCMSP) was used to screen 14 effective active ingredients and 218 targets of C. chinensis. The GeneCards, OMIM, and PharmGkb databases were used to screen 3517 disease targets for PCOS, and 102 common targets of drugs and diseases were screened using R Cytoscape that was utilized to build a drug-active ingredient-disease target interaction network, and the STRING platform was utilized to construct a common target protein-protein interaction network, including 102 nodes and 221 edges. Key targets of C. chinensis for the treatment of PCOS included JUN, MAPK, IL6, CXCL8, FOS, and IL1B. A total of 123 gene ontology (GO) terms and 129 pathways were acquired by GO and KEGG enrichment analyses. The AGEs/RAGE, TNF, IL-17, MAPK, and HIF-1 signaling pathways were closely related to PCOS and may be the core pathways involved in PCOS. Schrodinger software was used to evaluate the interaction between active components and their targets and explore binding modes. Furthermore, based on the prediction of network pharmacology study, a mouse model of PCOS was established to evaluate the curative role and underlying mechanisms of C. chinensis. The results showed that C. chinensis treatment reversed histopathological damage of the ovary and also ameliorated the mRNA and protein expression levels of the predicted hub targets (MAPK1, CXCL8, IL-6, and IL-1β). These results indicated that WZYZP has a protective effect on spermatogenesis disorder, suggesting that it could be an alternative choice for male infertility therapy.

Conclusions

This preliminary study verified the basic pharmacological effects and mechanisms of C. chinensis, a TCM, in the treatment of PCOS. These results indicate that the therapeutic effects of C. chinensis on PCOS may be achieved by regulating the expression of inflammatory factors. This study provides new insights for the systematic exploration of the mechanism of traditional Chinese medicine.

Oxidative stress in oocyte aging and female reproduction

In a healthy body, reactive oxygen species (ROS) and antioxidants remain balanced. When the balance is broken toward an overabundance of ROS, oxidative stress appears and may lead to oocyte aging. Oocyte aging is mainly reflected as the gradual decrease of oocyte quantity and quality. Here, we aim to review the relationship between oxidative stress and oocyte aging. First, we introduced that the defective mitochondria, the age-related ovarian aging, the repeated ovulation, and the high-oxygen environment were the ovarian sources of ROS in vivo and in vitro. And we also introduced other sources of ROS accumulation in ovaries, such as overweight and unhealthy lifestyles. Then, we figured that oxidative stress may act as the "initiator" for oocyte aging and reproductive pathology, which specifically causes follicular abnormally atresia, abnormal meiosis, lower fertilization rate, delayed embryonic development, and reproductive disease, including polycystic ovary syndrome and ovary endometriosis cyst. Finally, we discussed current strategies for delaying oocyte aging. We introduced three autophagy antioxidant pathways like Beclin-VPS34-Atg14, adenosine 5'-monophosphate (AMP)-activated protein kinase/mammalian target of rapamycin (AMPK/mTOR), and p62-Keap1-Nrf2. And we also describe the different antioxidants used to combat oocyte aging. In addition, the hypoxic (5% O₂ ) culture environment for oocytes avoiding oxidative stress in vitro. So, this review not only contribute to our general understanding of oxidative stress and oocyte aging but also lay the foundations for the therapies to treat premature ovarian failure and oocyte aging in women.

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

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

Advanced Glycation End Products Enhance Biofilm Formation by Promoting Extracellular DNA Release Through sigB Upregulation in Staphylococcus aureus

Bacterial biofilms do serious harm to the diabetic foot ulcer (DFU) because they play a crucial role in infection invasion and spread. Staphylococcus aureus, the predominant Gram-positive bacteria in diabetic foot infection (DFI), is often associated with colonization and biofilm formation. Through biofilm formation tests in vitro, we observed that S. aureus bacteria isolated from DFU wounds were more prone to form biofilms than those from non-diabetic patients, while there was no difference in blood sugar between the biofilm (+) diabetics (DB+) and biofilm (-) diabetics (DB-). Furthermore, we found that advanced glycation end products (AGEs) promoted the biofilm formation of S. aureus in clinical isolates and laboratory strains in vitro, including a methicillin-resistant strain. Analysis of biofilm components demonstrated that the biofilms formed mainly by increasing extracellular DNA (eDNA) release; remarkably, the S. aureus global regulator sigB was upregulated, and its downstream factor lrgA was downregulated after AGE treatments. Mechanism studies using a sigB-deleted mutant (Newman-ΔsigB) confirmed that AGEs decreased expression of lrgA via induction of sigB, which is responsible for eDNA release and is a required component for S. aureus biofilm development. In conclusion, the present study suggests that AGEs promote S. aureus biofilm formation via an eDNA-dependent pathway by regulating sigB. The data generated by this study will provide experimental proof and theoretical support to improve DFU infection healing.

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

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

Autophagy in Female Fertility: A Role in Oxidative Stress and Aging

Significance: The precipitous age-related decline in female fertility is intimately associated with a reduction in both the quantity and quality of the germline (oocytes). Although complex etiologies undoubtedly contribute to the deterioration of oocyte quality, increasing attention has focused on the pervasive impact of oxidative stress. Indeed, the prolonged lifespan of the meiotically arrested oocyte places this cell at heightened risk of oxidative lesions, which commonly manifest in dysregulation of protein homeostasis (proteostasis). Although oocytes are able to mitigate this threat via the mobilization of a sophisticated network of surveillance, repair, and proteolytic pathways, these defenses are themselves prone to age-related defects, reducing their capacity to eliminate oxidatively damaged proteins. Recent Advances: Here, we give consideration to the quality control mechanisms identified within the ovary that afford protection to the female germline. Our primary focus is to review recent advances in our understanding of the autophagy pathway and its contribution to promoting oocyte longevity and modulating pathophysiological responses to oxidative stress. In addition, we explore the therapeutic potential of emerging strategies to fortify autophagic activity. Critical Issues: The complex interplay of oxidative stress and autophagy has yet to be fully elucidated within the context of the aging oocyte and surrounding ovarian environment. Future Directions: Emerging evidence provides a strong impetus to resolve the causal link between autophagy and oxidative stress-driven pathologies in the aging oocyte. Such research may ultimately inform novel therapeutic strategies to combat the age-related loss of female fertility via fortification of intrinsic autophagic activity.

The effect of controlled reperfusion on experimental ovarian torsion

The objective of our research was to study the effect of controlled reperfusion on lactate and advanced oxidation protein products (AOPP) in experimental ovarian torsion (OT), and to evaluate the possibility to reduce the reperfusion injuries applying the ON-OFF technique of reperfusion. Material and Methods — Lactate and AOPP were measured in serum and ovarian homogenates of 70 females rats, divided equally into 7 groups: no intervention (nr. 1); laparotomy (nr. 2); 3 hours OT (nr. 3); 3 hours OT + 1 hour (nr. 4) or 24 hours (nr. 6) of simple reperfusion (SR); 3 hours OT + 1 hour (nr. 5) or 24 hours (nr. 7) of controlled reperfusion (ON-OFF). The results were analyzed using Welch's ANOVA. Results — OT produced an increase of serum (66%, p<0.001) and homogenate (38%, p=0.006) lactate, that tended to return to baseline in 24 hours despite the type of reperfusion. AOPP had grown in OT animals serum (20%, p=0.007) and homogenate (26%, p>0.05) and continued to rise in the serum after SR, while in ON-OFF technique groups – decreased by about 20% (p<0.01). Homogenate AOPP levels rised after reperfusion in all groups. Conclusion — Lactate is a biomarker for ischemia in OT. Increased AOPP in experimental groups indicates that there is a degree of oxidative stress that can affect the cells after the restoration of the blood flow. Therefore, the correct management of the condition that reduces reactive oxygen species production, such as controlled method of reperfusion, could be appropriate to prevent additional injuries.

Increased advanced glycation end products in hypertrophied ligamentum flavum of diabetes mellitus patients

BACKGROUND CONTEXT

Ligamentum flavum (LF) hypertrophy plays a dominant role in lumbar spinal stenosis (LSS). Although LSS prevalence is known to be higher in patients with diabetes mellitus (DM), the underlying pathomechanisms are not well understood. Abnormal advanced glycation end products (AGEs) formation occurs in DM and promotes tissue damage in various organs through degeneration and inflammation.

PURPOSE

To analyze and compare LF histology focused on AGE status between control patients, LSS patients with DM, and LSS patients without DM.

STUDY DESIGN/SETTING

Basic research study design utilizing human LF tissue for histologic analyses.

PATIENT SAMPLE

LF tissue samples were collected from patients who underwent lumber decompression surgery for LSS in the author's institution.

OUTCOME MEASURES

Quantitative visualization of Masson's Trichrome (MT) stains, and AGE immunohistochemistry (IHC) for the three groups.

METHODS

Ten LF specimens from LSS patients with DM (DM group, mean age 71.4 years), 10 from LSS patients without DM (non-DM group, mean age 71.2 years), and 9 from patients with lumbar disc herniation or cauda equina tumor (control group, mean age 49.0 years) were harvested during surgery and histologically analyzed. Percentage of elastic fiber areas (%EF) was measured with MT staining, and the percentage of AGE immuno-positive areas (%AGEs) was measured with IHC.

RESULTS

The average %EFs were 12.8 in the DM group, 17.1 in the non-DM group, and 24.9 in the control group. The decrease in the elastic fibers was significantly more in the DM group than in the non-DM (p<.01) and control groups (p<.001). Accumulation of AGEs was found mainly in the extracellular matrix in areas of elastic fiber disruption. The %AGEs were 18.3 in the DM group, 12.1 in the non-DM group, and 4.6 in the control group. These were significantly larger in the DM group than in the non-DM (p<.01) and control (p<.01) groups. The %AGEs also positively correlated with patient age (p<.01, R=0.47).

CONCLUSIONS

Accumulation of AGEs is significantly greater in the LF of DM patients and correlates with patient age. AGEs may accelerate degeneration and hypertrophy of LF with age and may lead to higher prevalence of LSS in patients with DM.

CLINICAL SIGNIFICANCE

The present results partly reveal the molecular mechanism of LF hypertrophy, suggesting that AGEs may be involved in the process of LF degeneration in the elderly and patients with DM.

Vitamin D attenuates the effect of advanced glycation end products on anti-Mullerian hormone signaling

Vitamin D3 (1,25-dihydroxyvitamin D3, VD3) in vitro attenuates the effect of the pro-inflammatory advanced glycation end products (AGEs) on steroidogenesis in human granulosa cells (GCs) by downregulating the receptor for AGEs (RAGE). It has been shown that VD3 alone downregulates anti-Mullerian hormone (AMH) type 2 receptor (AMHR-2) gene expression and suppresses AMH-induced SMAD 1/5/8 phosphorylation in granulosa cells. However, the effect of AGEs, in the absence or presence of VD3, on AMH action in GCs has not been studied. Using human GCs, this study showed that human glycated albumin (HGA), an in vitro representative for AGEs, upregulated AMHR-2 mRNA but did not alter AMH mRNA expression levels. VD3 inhibited the HGA-induced increase in AMHR-2 mRNA expression levels. In KGN granulosa cell line, recombinant AMH induced SMAD 1/5/8 phosphorylation. HGA augmented the recombinant AMH-induced SMAD 1/5/8 phosphorylation while the addition of VD3 to HGA attenuated the recombinant AMH-induced SMAD 1/5/8 phosphorylation. Thus, AGEs could potentially affect folliculogenesis as reflected by changes in AMH signaling. These findings have significant implications for women with polycystic ovary syndrome who have significantly elevated serum and ovarian AGEs.

Age-associated deterioration in follicular fluid induces a decline in bovine oocyte quality

Maternal age affects the quality of oocytes. The present study examined whether follicular fluid (FF) is a casual factor for age-associated decline in oocyte quality. First, we measured the concentration of advanced glycation end-products (AGE) in FF derived from young (21-45 months; Young-FF) and aged (≥120 months; Aged-FF) cows and found significantly higher concentrations of AGE in Aged-FF than Young-FF. Second, oocytes were collected from ovaries of young or aged cows and cultured in maturation medium containing 10% FF derived from young or aged cows. Regardless of oocyte origin, Aged-FF accelerated nuclear maturation progression and gap junction closure between oocytes and cumulus cells, increased reactive oxygen species (ROS) content and the rate of abnormal fertilisation of oocytes and decreased blastulation rate compared with Young-FF. Furthermore, supplementation of maturation medium with AGE induced similar age-associated events in oocytes derived from young cows, in that AGE accelerated the progression of nuclear maturation, increased ROS content in oocytes, increased the rate of abnormal fertilisation and decreased blastulation rate. In conclusion, maternal aging increased the concentration of AGE in FF, and both AGE and Aged-FF accelerated nuclear maturation and reduced the developmental competence of oocytes.

Targeted metabolomics reveals reduced levels of polyunsaturated choline plasmalogens and a smaller dimethylarginine/arginine ratio in the follicular fluid of patients with a diminished ovarian reserve

STUDY QUESTION

Does the metabolomic profile of the follicular fluid (FF) of patients with a diminished ovarian reserve (DOR) differ from that of patients with a normal ovarian reserve (NOR)?

SUMMARY ANSWER

The metabolomic signature of the FF reveals a significant decrease in polyunsaturated choline plasmalogens and methyl arginine transferase activity in DOR patients compared to NOR patients.

WHAT IS KNOWN ALREADY

The composition of the FF reflects the exchanges between the oocyte and its microenvironment during its acquisition of gametic competence. Studies of the FF have allowed identification of biomarkers and metabolic pathways involved in various pathologies affecting oocyte quality, but no large metabolomic analysis in the context of ovarian ageing and DOR has been undertaken so far.

STUDY DESIGN, SIZE, DURATION

This was an observational study of the FF retrieved from 57 women undergoing in vitro fertilization at the University Hospital of Angers, France, from November 2015 to September 2016. The women were classified in two groups: one including 28 DOR patients, and the other including 29 NOR patients, serving as controls.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Patients were enrolled in the morning of oocyte retrieval after ovarian stimulation. Once the oocytes were isolated for fertilization and culture, the FF was pooled and centrifuged for analysis. A targeted quantitative metabolomic analysis was performed using high-performance liquid chromatography coupled with tandem mass spectrometry, and the Biocrates Absolute IDQ p180 kit. The FF levels of 188 metabolites and several sums and ratios of metabolic significance were assessed by multivariate and univariate analyses.

MAIN RESULTS AND THE ROLE OF CHANCE

A total of 136 metabolites were accurately quantified and used for calculating 23 sums and ratios. Samples were randomly divided into training and validation sets. The training set, allowed the construction of multivariate statistical models with a projection-supervised method, i.e. orthogonal partial least squares discriminant analysis (OPLS-DA), applied to the full set of metabolites, or the penalized least absolute shrinkage and selection operator with logistic regression (LASSO-LR), applied to the ratios and sums of the metabolites. Both multivariate models showed good predictive performances when applied to the validation set. The final penalized model retained the three most significant variables, i.e. the total dimethylarginine-to-arginine ratio (Total DMA/Arginine), the sum of the polyunsaturated choline plasmalogens (PUFA ae), and the patient's age. The negative coefficients of Total DMA/Arginine and PUFA ae indicated that these FF variables had lower values in DOR patients than in NOR patients.

LARGE SCALE DATA

N/A.

LIMITATIONS REASONS FOR CAUTION

This study presents two limitations. First, with this targeted metabolomics analysis, we have explored only a limited portion of the FF metabolome. Second, although the signature found was highly significant, the mechanism underlying the dysfunction remains undetermined.

WIDER IMPLICATIONS OF THE FINDINGS

The understanding of the mechanisms implied in ovarian ageing is essential for providing an adequate response to affected women desiring pregnancy. Our study proposes an incoming signature that may open new paths towards this goal.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by the University Hospital of Angers, the University of Angers, and the French national research centers, INSERM and the CNRS. There were no competing interests.

Advanced glycation end products alter steroidogenic gene expression by granulosa cells: an effect partially reversible by vitamin D

STUDY QUESTION

Does vitamin D attenuate the adverse effects of advanced glycation end products (AGEs) on steroidogenesis by human granulosa cells (GCs)?

SUMMARY ANSWER

AGEs alter the expression of genes important in steroidogenesis while 1,25-dihydroxyvitamin D3 (vit D3) in vitro attenuates some of the actions of AGEs on steroidogenic gene expression, possibly by downregulating the expression of the pro-inflammatory cell membrane receptor for AGEs (RAGE).

WHAT IS KNOWN ALREADY

Vitamin D attenuates the pro-inflammatory effects of AGEs in non-ovarian tissues.

STUDY DESIGN, SIZE, DURATION

Women who were undergoing IVF were enrolled. Follicular fluid samples (n = 71) were collected and cumulus GCs (n = 12) were treated in culture.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Follicular fluid levels of the anti-inflammatory soluble RAGE (sRAGE), AGEs and 25-hydroxyvitamin D (25-OHD) were quantified for possible correlations. GCs of each participant were split equally and treated with either media alone (control) or with human glycated albumin (HGA as a precursor for AGEs) with or without vit D3 after which RT-PCR and immunofluorescence were performed and cell culture media estradiol (E2) levels were compared.

MAIN RESULTS AND THE ROLE OF CHANCE

In follicular fluid, sRAGE levels were positively correlated with 25-OHD levels. HGA treatment (i) increased CYP11A1 (by 48%), 3β-HSD (by 38%), StAR (by 42%), CYP17A1 (by 30%) and LHR (by 37%) mRNA expression levels (P < 0.05 for all) but did not alter CYP19A1 or FSHR mRNA expression levels; and (ii) increased E2 release in cell culture media (P = 0.02). Vit D3 treatment (i) downregulated RAGE mRNA expression by 33% and RAGE protein levels by 44% (P < 0.05); (ii) inhibited the HGA-induced increase in CYP11A1, StAR, CYP17A1 and LHR mRNA levels, but not the increase in 3β-HSD mRNA levels; and (iii) did not inhibit the HGA-induced E2 release in cell culture media.

LIMITATIONS REASONS FOR CAUTION

This study used luteinized GCs that were collected from women who received gonadotropins thus the results obtained may not fully extrapolate to non-luteinized GCs in vivo.

WIDER IMPLICATIONS OF THE FINDINGS

This study suggests that there is a relationship between AGEs and their receptors (RAGE and sRAGE) with vitamin D. Understanding the interaction between AGEs and vitamin D in ovarian physiology could lead to a more targeted therapy for the treatment of ovarian dysfunction.

STUDY FUNDING/COMPETING INTEREST(S)

Funding was received from NIH (R01 NS045940), American Society for Reproductive Medicine, Ferring Pharmaceuticals Inc., and University of Vermont College of Medicine Bridge Funds. All authors have nothing to disclose.

Aging ovary and the role for advanced glycation end products

OBJECTIVE

The hypothalamic gonadotropin-releasing hormone pulse generator, the pituitary gonadotropes, the ovaries, and the uterus play a crucial role in female fertility. A decline in reproductive performance represents a complex interplay of actions at all levels of the hypothalamic-pituitary-ovarian axis. Recently, in the field of female reproductive aging attention is drawn to the carbonyl stress theory. Advanced glycation end products (AGEs) contribute directly to protein damage, induce a chain of oxidative stress (OS) reactions, and increase inflammatory reactions. Here, we highlight some of the mechanisms underlying glycation damage in the ovary.

METHODS

Searches of electronic databases were performed. Articles relevant to possible role of OS, AGEs, and receptor for AGE (RAGE) in aging ovary were summarized in this interpretive literature review.

RESULTS

Follicular microenvironment undergoes an increase in OS with aging. Data support the role of OS in ovulatory dysfunction because AGEs are well-recognized mediators of increased OS. RAGE and AGE-modified proteins with activated nuclear factor-kappa B are expressed in human ovarian tissue. It was suggested that accumulation of AGEs products at the level of the ovarian follicle might trigger early ovarian aging or could be responsible for reduced glucose uptake by granulosa cells, potentially altering follicular growth. Moreover, impaired methylglyoxal detoxification causing relevant damage to the ovarian proteome might be one of the mechanisms underlying reproductive aging.

CONCLUSIONS

Further investigation of the role for the AGE-RAGE axis in the ovarian follicular environment is needed, and results could relate to assisted reproduction technology outcomes and new measures of ovarian reserve.

Molecular Mechanisms Responsible for Increased Vulnerability of the Ageing Oocyte to Oxidative Damage

In their midthirties, women experience a decline in fertility, coupled to a pronounced increase in the risk of aneuploidy, miscarriage, and birth defects. Although the aetiology of such pathologies are complex, a causative relationship between the age-related decline in oocyte quality and oxidative stress (OS) is now well established. What remains less certain are the molecular mechanisms governing the increased vulnerability of the aged oocyte to oxidative damage. In this review, we explore the reduced capacity of the ageing oocyte to mitigate macromolecular damage arising from oxidative insults and highlight the dramatic consequences for oocyte quality and female fertility. Indeed, while oocytes are typically endowed with a comprehensive suite of molecular mechanisms to moderate oxidative damage and thus ensure the fidelity of the germline, there is increasing recognition that the efficacy of such protective mechanisms undergoes an age-related decline. For instance, impaired reactive oxygen species metabolism, decreased DNA repair, reduced sensitivity of the spindle assembly checkpoint, and decreased capacity for protein repair and degradation collectively render the aged oocyte acutely vulnerable to OS and limits their capacity to recover from exposure to such insults. We also highlight the inadequacies of our current armoury of assisted reproductive technologies to combat age-related female infertility, emphasising the need for further research into mechanisms underpinning the functional deterioration of the ageing oocyte.

MECHANISMS IN ENDOCRINOLOGY: Aging and anti-aging: a Combo-Endocrinology overview

Aging and its underlying pathophysiological background has always attracted the attention of the scientific society. Defined as the gradual, time-dependent, heterogeneous decline of physiological functions, aging is orchestrated by a plethora of molecular mechanisms, which vividly interact to alter body homeostasis. The ability of an organism to adjust to these alterations, in conjunction with the dynamic effect of various environmental stimuli across lifespan, promotes longevity, frailty or disease. Endocrine function undergoes major changes during aging, as well. Specifically, alterations in hormonal networks and concomitant hormonal deficits/excess, augmented by poor sensitivity of tissues to their action, take place. As hypothalamic-pituitary unit is the central regulator of crucial body functions, these alterations can be translated in significant clinical sequelae that can impair the quality of life and promote frailty and disease. Delineating the hormonal signaling alterations that occur across lifespan and exploring possible remedial interventions could possibly help us improve the quality of life of the elderly and promote longevity.

Intrafollicular soluble RAGE benefits embryo development and predicts clinical pregnancy in infertile patients of advanced maternal age undergoing in vitro fertilization

Soluble receptor for advanced glycation end products (sRAGE) can decoy the toxic AGEs and is considered to be a protective factor. This study aimed to evaluate the correlation between intrafollicular sRAGE levels and clinical outcomes in infertile women of young or advanced maternal age (AMA) undergoing in vitro fertilization (IVF). A total of 62 young women and 62 AMA women who would undergo IVF were included in this prospective study. The intrafollicular sRAGE concentration was measured to determine its association with the number of retrieved oocytes, fertilized oocytes, high-quality embryos or achievement of clinical pregnancy in young and AMA women, respectively. Besides, correlations between sRAGE and age or follicle-stimulating hormone (FSH) were examined. We found that the intrafollicular sRAGE levels were higher in young patients than those in AMA patients, suggesting that the sRAGE levels were inversely correlated with age. In young patients, sRAGE showed no correlation with the number of retrieved oocytes, fertilized oocytes, high-quality embryos or achievement of clinical pregnancy. But it was found that AMA patients with more retrieved oocytes, fertilized oocytes and high-quality embryos demonstrated higher sRAGE levels, which were a prognostic factor for getting clinical pregnancy independent of age or FSH level. In conclusion, the sRAGE levels decrease with age. Elevated intrafollicular sRAGE levels indicate good follicular growth, fertilization and embryonic development, and successful clinical pregnancy in AMA women, while in young women, the role of sRAGE may not be so predominant.

MECHANISMS IN ENDOCRINOLOGY: Nutrition as a mediator of oxidative stress in metabolic and reproductive disorders in women

Nutrition can generate oxidative stress and trigger a cascade of molecular events that can disrupt oxidative and hormonal balance. Nutrient ingestion promotes a major inflammatory and oxidative response at the cellular level in the postprandial state, altering the metabolic state of tissues. A domino of unfavorable metabolic changes is orchestrated in the main metabolic organs, including adipose tissue, skeletal muscle, liver and pancreas, where subclinical inflammation, endothelial dysfunction, mitochondrial deregulation and impaired insulin response and secretion take place. Simultaneously, in reproductive tissues, nutrition-induced oxidative stress can potentially violate delicate oxidative balance that is mandatory to secure normal reproductive function. Taken all the above into account, nutrition and its accompanying postprandial oxidative stress, in the unique context of female hormonal background, can potentially compromise normal metabolic and reproductive functions in women and may act as an active mediator of various metabolic and reproductive disorders.

Expression pattern of RAGE and IGF-1 in the human fetal ovary and ovarian serous carcinoma

The expression pattern of RAGE and IGF-1 proteins in different ovarian cell lineages was histologically analyzed in six fetal, nine adult human ovaries, and nine serous ovarian carcinomas (OSC) using immunohistochemical methods. Mild expression of IGF-1 in ovarian surface epithelium (Ose) and oocytes in the 15-week human ovaries increased to moderate or strong in the stromal cells, oocytes and follicular cells in week 22. Occasional mild RAGE expression was observed in Ose during week 15, while strong expression characterized primordial follicles in week 22. In the reproductive human ovary, IGF-1 was mildly to moderately expressed in all ovarian cell lineages except in theca cells of the tertiary follicle where IGF-1 was negative. RAGE was strongly positive in the granulosa cells and some theca cells of the tertiary follicle, while negative to mildly positive in all cells of the secondary follicle. In the postmenopausal human ovary IGF-1 and RAGE were mildly expressed in Ose and stroma. In OSC, cells were strongly positive to IGF-1 and RAGE, except for some negative stromal cells. Different levels of IGF-1 and RAGE co-expression characterized fetal ovarian cells during development. In reproductive ovaries, IGF-1 and RAGE were co-localized in the granulosa and theca interna cells of tertiary follicles, while in postmenopausal ovaries and OSC, IGF-1 and RAGE were co-localized in Ose and OSC cells respectively. Our results indicate that intracellular levels of IGF-1 and RAGE protein might regulate the final destiny of the ovarian cell populations prior and during folliculogenesis, possibly controlling the metastatic potential of OSC as well.

Oxidative stress, protein glycation and nutrition--interactions relevant to health and disease throughout the lifecycle

Protein glycation has been studied for over a century now and plays an important role in disease pathogenesis throughout the lifecycle. Strongly related to diabetic complications, glycation of Hb has become the gold standard method for diabetes diagnosis and monitoring. It is however attracting attention in normoglycaemia as well lately. Longitudinal studies increasingly suggest a positive relationship between glycation and the risk of chronic diseases in normoglycaemic individuals, but the mechanisms behind this association remain unclear. The interaction between glycation and oxidative stress may be particularly relevant in the normoglycaemic context, as suggested by recent epidemiological and in vitro evidence. In that context nutritional and lifestyle factors with an influence on redox status, such as smoking, fruit and vegetable and antioxidants consumption, may have the capacity to promote or inhibit glycation. However, experimental data from controlled trials are lacking the quality and rigour needed to reach firm conclusions. In the present review, we discuss the importance of glycation for health through the lifecycle and focus on the importance of oxidative stress as a driver for glycation. The importance of nutrition to modulate glycation is discussed, based on the evidence available and recommendations towards higher quality future research are made.

Dicarbonyl stress and glyoxalases in ovarian function

The ovary is the main regulator of female fertility. Changes in maternal health and physiology can disrupt intraovarian homoeostasis thereby compromising oocyte competence and fertility. Research has only recently devoted attention to the involvement of dicarbonyl stress in ovarian function. On this basis, the present review focuses on clinical and experimental research supporting the role of dicarbonyl overload and AGEs (advanced glycation end-products) as key contributors to perturbations of the ovarian microenvironment leading to lower fertility. Particular emphasis has been given to oocyte susceptibility to methylglyoxal, a powerful glycating agent, whose levels are known to increase during aging and metabolic disorders. According to the literature, the ovary and the oocyte itself can rely on the glyoxalase system to counteract the possible dicarbonyl overload such as that which may occur in reproductive-age women and patients with PCOS (polycystic ovarian syndrome) or diabetes. Overall, although biochemical methods for proper evaluation of dicarbonyl stress in oocytes and the ovarian microenvironment need to be established, AGEs can be proposed as predictive markers and/or therapeutic targets in new strategies for improving reproductive counselling and infertility therapies.