The role of advanced glycation end products in human infertility

Navigating the Intersection of Glycemic Control and Fertility: A Network Perspective

The rising incidence of metabolic diseases is linked to elevated blood glucose levels, contributing to conditions such as diabetes and promoting the accumulation of advanced glycation end products (AGEs). AGEs, formed by non-enzymatic reactions between sugars and proteins, build up in tissues and are implicated in various diseases. This article explores the relationship between glycemic control and AGE accumulation, focusing on fertility implications. A computational model using network theory was developed, featuring a molecular database and a network with 145 nodes and 262 links, categorized as a Barabasi-Albert scale-free network. Three main subsets of nodes emerged, centered on glycemic control, fertility, and immunity, with AGEs playing a critical role. The transient receptor potential vanilloid 1 (TRPV1), a receptor expressed in several tissues including sperm, was identified as a key hub, suggesting that the modulation of TRPV1 in sperm by AGEs may influence fertility. Additionally, a novel link between glycemic control and immunity was found, indicating that immune cells may play a role in endocytosing specific AGEs. This discovery underscores the complex interplay between glycemic control and immune function, with significant implications for metabolic, immune health, and fertility.

Unraveling the molecular pathogenesis of Type 2 Diabetes and its impact on female infertility: A bioinformatics and systems biology approach

Type 2 diabetes mellitus (T2D) has been linked with female infertility (FI). Nevertheless, our understanding of the molecular hallmarks and underlying mechanisms remains elusive. This research article aimed to find the hub genes, pathways, transcription factors, and miRNA involved. For this study, softwares like cytoscape, string, Enrichr, FFL loop, etc., were utilized. This research article employed differentially expressed genes (DEGs) to identify multiple biological targets to understand the association between T2D and female infertility (FI). Between T2D and FI, we found 3869 differentially expressed genes. We have also analyzed different pathways like thyroid hormone signaling pathways, AGE-RAGE signaling pathways in diabetic complications and ubiquitin-mediated proteolysis through pathway analysis. Moreover, hub genes MED17, PRKCG, THRA, FOXO1, NCOA2, PLCG2, COL1A1, CXCL8, PRPF19, ANAPC5, UBE2I, XIAP and KEAP1 have been identified. Additionally, these hub genes were subjected to identify the miRNA-mRNA regulation network specific to T2D-associated female infertility. In the FFL study (Feed Forward Loop), transcription factor (SP1, NFKB1, RELA and FOX01), miRNA (has-mir-7-5p, has-let-7a-5p, hsa-mir-16-5p, hsa-mir-155-5p, has-mir-122-5p, has-let-7b-5p, has-mir-124-3p, has-mir-34a-5p, has-mir-130a-3p, has-let-7i-5p, and hsa-mir-27a-3p) and six genes (XIAP, THRA, NCOA2, MED17, FOXO1, and COL1A1) among the thirteen key genes were recognized as regulator and inhibitor. Our analysis reveals that these genes can serve as a significant biomarker for female infertility linked with Type 2 Diabetes, through the prioritization of candidate genes. This study gives us insight into the molecular and cellular mechanism of T2D-associated FI. This finding helps in developing novel therapeutic approaches and will improve efficacy and reduce side effects of the treatment. This research requires further experimental investigation of the principal targets.

Effect of Advanced Glycation end Products (AGEs) on Sperm Parameters and Function in C57Bl/6 Mice

This study investigated the deleterious impact of advanced glycation end products (AGEs), commonly present in metabolic disorders like diabetes, obesity, and infertility-related conditions, on sperm structure and function using a mouse model where AGE generation was heightened through dietary intervention. Five-week-old C57BL/6 mice were divided into two groups, one on a regular diet (control) and the other on an AGE-rich diet. After 13 weeks, various parameters were examined, including fasting blood glucose, body weight, food consumption, sperm parameters and function, testicular superoxide dismutase levels, malondialdehyde content, total antioxidant capacity, Johnson score, AGE receptor (RAGE) content, and carboxymethyl lysine (CML) content. The results showed that mice in the AGE group exhibited increased body weight and elevated fasting blood glucose levels. Furthermore, the AGE group displayed adverse effects on sperm, including reduced sperm counts, motility, increased morphological abnormalities, residual histone, protamine deficiency, sperm DNA fragmentation, reduced testicular antioxidant capacity, and higher levels of RAGE and CML proteins. These findings underscore the negative impact of AGEs on male reproductive health, particularly within the context of metabolic disorders, emphasizing the crucial role of the AGE/RAGE axis in male infertility, especially in the context of Western dietary patterns.

Maternal nutrition and fetal imprinting of the male progeny

The global population as well as the demand for human food is rapidly growing worldwide, which necessitates improvement of efficiency in livestock operations. In this context, environmental factors during fetal and/or neonatal life have been observed to influence normal physical and physiological function of an individual during adulthood, and this phenomenon is called fetal or developmental programming. While numerous studies have reported the impact of maternal factors on development of the female progeny, limited information is available on the potential effects of fetal programming on reproductive function of the male offspring. Therefore, the objective for this review article was to focus on available literature regarding the impact of maternal factors, particularly maternal nutrition, on reproductive system of the male offspring. To this end, we highlighted developmental programming of the male offspring in domestic species (i.e., pig, cow and sheep) as well as laboratory species (i.e., mice and rat) during pregnancy and lactation. In this sense, we pointed out the effects of maternal nutrition on various functions of the male offspring including hypothalamic-pituitary axis, hormonal levels, testicular tissue and semen parameters.

The effect of coenzyme Q10 intake on metabolic profiles in women candidates for in-vitro fertilization: a randomised trial

Objective

Infertility and the pathogenesis of polycystic ovarian syndrome (PCOS) are both influenced by insulin resistance and dyslipidemia. Presumably, adding coenzyme Q10 (CoQ10) to these patients' diets will be beneficial. Therefore, this study aimed to examine the effects of CoQ10 supplementation on metabolic profiles in women candidates for in-vitro fertilization (IVF).

Trial design and methods

For this randomized, double-blinded, parallel, placebo-controlled clinical experiment, 40 PCOS-positive infertile women who were IVF candidates were included. They ranged in age from 18 to 40. The 20 participants in the two intervention groups received either CoQ10 or a placebo for 8 weeks. The expression of glucose transporter 1 (GLUT-1), peroxisome proliferator-activated receptor gamma (PPAR-γ), low-density lipoprotein receptor (LDLR), as well as metabolic profiles such as insulin metabolism and lipid profiles were evaluated. Quantitative RT-PCR determined the expression of GLUT-1, PPAR-γ, and LDLR on peripheral blood mononuclear cells. Lipid profiles and fasting glucose were assessed using enzymatic kits, and insulin was determined using Elisa kit.

Results

In comparison to the placebo, CoQ10 supplementation significantly reduced blood insulin levels (-0.3±1.0 vs. 0.5±0.7, P=0.01) and insulin resistance (-0.1±0.2 vs. 0.1±0.2, P=0.01), and increased PPAR-γ expression (P=0.01). In infertile PCOS patients' candidates for IVF, CoQ10 supplementation showed no appreciable impact on other metabolic profiles. Also, CoQ10 supplementation revealed no significant impact on GLUT-1 (P=0.30), or LDLR (P=0.27) expression. Within-group changes in insulin levels (P=0.01) and insulin resistance (P=0.01) showed a significant elevation in the placebo group. When we adjusted the analysis for baseline BMI, baseline values of variables, and age, our findings were not affected.

Conclusions

Eight weeks of CoQ10 supplementation demonstrated positive benefits on PPAR-γ expression, insulin resistance, and serum insulin in infertile PCOS women candidates for IVF.

Cancer risk and male Infertility: Unravelling predictive biomarkers and prognostic indicators

In recent years, there has been a global increase in cases of male infertility. There are about 30 million cases of male infertility worldwide and male reproductive health is showing rapid decline in last few decades. It is now recognized as a potential risk factor for developing certain types of cancer, particularly genitourinary malignancies like testicular and prostate cancer. Male infertility is considered a potential indicator of overall health and an early biomarker for cancer. Cases of unexplained male factor infertility have high levels of oxidative stress and oxidative DNA damage and this induces both denovo germ line mutations and epimutations due to build up of 8-hydroxy 2 deoxygunaosine abase which is highly mutagenic and also induces hypomethylation and genomic instability. Consequently, there is growing evidence to explore the various factors contributing to an increased cancer risk. Currently, the available prognostic and predictive biomarkers associated with semen characteristics and cancer risk are limited but gaining significant attention in clinical research for the diagnosis and treatment of elevated cancer risk in the individual and in offspring. The male germ cell being transcriptionally and translationally inert has a highly truncated repair mechanism and has minimal antioxidants and thus most vulnerable to oxidative injury due to environmental factors and unhealthy lifestyle and social habits. Therefore, advancing our understanding requires a thorough evaluation of the pathophysiologic mechanisms at the DNA, RNA, protein, and metabolite levels to identify key biomarkers that may underlie the pathogenesis of male infertility and associated cancer. Advanced methodologies such as genomics, epigenetics, proteomics, transcriptomics, and metabolomics stand at the forefront of cutting-edge approaches for discovering novel biomarkers, spanning from infertility to associated cancer types. Henceforth, in this review, we aim to assess the role and potential of recently identified predictive and prognostic biomarkers, offering insights into the success of assisted reproductive technologies, causes of azoospermia and idiopathic infertility, the impact of integrated holistic approach and lifestyle modifications, and the monitoring of cancer susceptibility, initiation and progression. Comprehending these biomarkers is crucial for providing comprehensive counselling to infertile men and cancer patients, along with their families.

Association between dietary inflammatory index and self-reported female infertility from the National Health and Nutrition Examination Survey 2013-2020

BACKGROUND

To explore the association between the diet inflammatory index (DII) and infertility.

METHODS

Multivariable logistic regression was performed to investigate the relationship between infertility and DII, and restricted cubic spline (RCS) was utilised to test for nonlinear relationships in this cross-sectional study. Data of this study were collected from the 2013 to 2020 National Health and Nutrition Examination Survey (NHANES) database. Considering women's child-bearing age, we enrolled a total of 2066 women aged 20-45 years in this study.

RESULTS

After all covariates were adjusted, a positive association was found between DII score and odds of infertility by multivariable logistic regression (odds ratio [OR] = 1.19, 95% confidence interval [CI] 1.03, 1.38; p = 0.027). Compared with participants with DII scores in the lowest quartile, those with DII scores in the highest quartile had significantly higher odds of infertility (OR = 2.42, 95% CI 1.09, 5.34; p = 0.034). The RCSs model suggested a linear relationship between DII and infertility (p for nonlinear = 0.1827).

CONCLUSIONS

A positive association between a pro-inflammatory diet and self-reported infertility was detected. Our study extends the application of the DII scoring system to infertility prevention.

Icariin protects testicular damage in streptozotocin-induced diabetic rats through regulation of glycolysis pathway

OBJECTIVE

This study aims to investigate potential beneficial actions of icariin (ICA) on testicular spermatogenic function in male rats with streptozotocin (STZ)-induced diabetes and to explore the underlying mechanisms. Background: ICA was found to reduce blood glucose, regulate the endocrine function of the reproductive system, and improve testicular spermatogenic function.

METHODS

Adult rats were intraperitoneally injected with STZ (65 mg/kg) to induce type 1 diabetes mellitus (T1DM). Diabetic rats were randomly classified intoT1DM (n = 6) and T1DM + ICA (n = 6) groups. Rats without STZ and ICA treatment were assigned as control group (n = 6). The morphology of testicular tissues was examined by histological staining. The mRNA and protein expression levels were determined by quantitative real-time PCR, Western blot and immunostaining, respectively.

RESULTS

Rats from T1DM group showed a reduction in epididymis and testis weight, and a decrease in sperm count when compared to control group (p < 0.01), which was attenuated by ICA treatment (p < 0.05) Diabetic rats from T1DM group also exhibited reduced diameter and area of seminiferous tubules, along with decreased spermatogonia and primary spermatocytes number when compared to control group (p < 0.01), which was partially reversed by ICA treatment (p < 0.05) Rats from T1DM group exhibited down-regulation of PCNA mRNA and protein in the testis when compared to control group (p < 0.01); while ICA treatment up-regulated PCNA expression in the testis of diabetic rats compared to T1DM group (p < 0.05). Rats from T1DM group showed up-regulation of Bax and capase-3 and down-regulation of Bcl-2, PKM2, HK2 and lactate dehydrogenase A in the testes when compared to control group (p < 0.05), which was reversed by ICA treatment (p < 0.05).

CONCLUSION

These findings suggest that ICA may exert its protective effects on testicular damage in diabetic rats through modulation of glycolysis pathway and suppression of apoptosis.

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.

Female infertility in the era of obesity: The clash of two pandemics or inevitable consequence?

Obesity is an epidemic that has led to a rise in the incidence of many comorbidities: among others, reduced fertility is often under-evaluated in clinical practice. The mechanisms underlying the link between reduced fertility and obesity are numerous, with insulin resistance, hyperglycaemia and the frequent coexistence of polycystic ovary syndrome being the most acknowledged. However, several other factors concur, such as gut microbiome alterations, low-grade chronic inflammation and oxidative stress. Not only do women with obesity take longer to conceive, but in vitro fertilization (IVF) is also less likely to succeed. We herein provide an updated state-of-the-art regarding the molecular bases of what we could define as dysmetabolic infertility, focusing on the clinical aspects, as well as possible treatment.

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.

Advanced Glycation End-Products (AGEs): Formation, Chemistry, Classification, Receptors, and Diseases Related to AGEs

Advanced glycation end-products (AGEs) constitute a non-homogenous, chemically diverse group of compounds formed either exogeneously or endogeneously on the course of various pathways in the human body. In general, they are formed non-enzymatically by condensation between carbonyl groups of reducing sugars and free amine groups of nucleic acids, proteins, or lipids, followed by further rearrangements yielding stable, irreversible end-products. In the last decades, AGEs have aroused the interest of the scientific community due to the increasing evidence of their involvement in many pathophysiological processes and diseases, such as diabetes, cancer, cardiovascular, neurodegenerative diseases, and even infection with the SARS-CoV-2 virus. They are recognized by several cellular receptors and trigger many signaling pathways related to inflammation and oxidative stress. Despite many experimental research outcomes published recently, the complexity of their engagement in human physiology and pathophysiological states requires further elucidation. This review focuses on the receptors of AGEs, especially on the structural aspects of receptor-ligand interaction, and the diseases in which AGEs are involved. It also aims to present AGE classification in subgroups and to describe the basic processes leading to both exogeneous and endogeneous AGE formation.

Proteome-wide and matrisome-specific atlas of the human ovary computes fertility biomarker candidates and open the way for precision oncofertility

Our modern era is witnessing an increasing infertility rate worldwide. Although some of the causes can be attributed to our modern lifestyle (e.g., persistent organic pollutants, late pregnancy), our knowledge of the human ovarian tissue has remained limited and insufficient to reverse the infertility statistics. Indeed, all efforts have been focused on the endocrine and cellular function in support of the cell theory that dates back to the 18th century, while the human ovarian matrisome is still under-described. Hereby, we unveil the extracellular side of the story during different periods of the ovary life, demonstrating that follicle survival and development, and ultimately fertility, would not be possible without its involvement. We examined the human ovarian matrisome and described its remodeling from prepuberty until menopause, creating the first ovarian proteomic codex. Here, we confidently identified and quantified 98 matrisome proteins present in the three ovary groups. Among them, 26 were expressed differently among age groups, delineating a peculiar matrisomal fingerprint at each stage. Such proteins could be potential biomarkers phenotyping ovarian ECM at each age phase of female reproductive life. Beyond proteomics, our study presents a unique approach to understanding the data and depicting the spatiotemporal ECM-intracellular signaling networks and remodeling with age through imaging, advanced text-mining based on natural language processing technology, machine learning, and data sonification. Our findings provide essential context for healthy ovarian physiology, identifying and characterizing disease states, and recapitulating physiological tissues or development in vitro. This comprehensive proteomics analysis represents the ovarian proteomic codex and contributes to an improved understanding of the critical roles that ECM plays throughout the ovarian life span.

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.

Trapa bispinosa Roxb. extract lowers advanced glycation end-products and increases live births in older patients with assisted reproductive technology: a randomized controlled trial

BACKGROUND

Advanced glycation end-products (AGE), which accumulate with insulin resistance and aging, impair folliculogenesis and may decrease endometrial receptivity. Hishi (Trapa bispinosa Roxb.) extract, a safe herbal medicine, strongly inhibits AGE formation in vitro. We determined whether Hishi lowers AGE and increases live births in older assisted reproductive technology (ART) patients.

METHODS

This prospective randomized open-label controlled trial included 64 patients 38 to 42 years old undergoing ART with or without Hishi extract between June 11, 2015 and July 12, 2019. None had over 2 ART failures, diabetes, uterine anomalies, or exhausted ovarian reserve. After allocation, the Hishi group received Hishi extract (100 mg/day) until late pregnancy or failure. The control group received no extract. Both groups underwent 1 cycle of conventional infertility treatment; 1 long-protocol cycle of ovarian stimulation, oocyte retrieval, in vitro fertilization/intracytoplasmic sperm injection, and fresh embryo transfer (ET); and, if needed, cryopreserved ET until live birth or embryo depletion. Serum AGE were measured before and during ART, as were AGE in follicular fluid (FF).

RESULTS

Cumulative live birth rate among 32 Hishi patients was 47%, significantly higher than 16% among 31 controls (p<0.01; RR, 4.6; 95% CI, 1.4 - 15.0; 1 control dropped out). Live birth rate per ET, including fresh and cryopreserved, was significantly higher with Hishi (28% in 47 ET vs. 10% in 49 ET; p<0.05; RR, 3.4; 95% CI, 1.1-10.4). Among variables including age, day-3 FSH, anti-Müllerian hormone, and Hishi, logistic regression identified only Hishi as significantly associated with increased cumulative live birth (p<0.05; OR, 5.1; 95% CI, 1.4 - 18.3). Hishi significantly enhanced oocyte developmental potential, improved endometrial receptivity in natural cycles, and decreased AGE in serum and FF. Larger serum AGE decreases with Hishi were associated with more oocytes becoming day-2 embryos.

CONCLUSIONS

Hishi decreased AGE in serum and FF and improved oocyte developmental potential and endometrial receptivity, increasing live births in older patients. Treatment of infertility by AGE reduction represents a new addition to infertility treatment. Therapeutic trials of Hishi for other AGE-associated diseases might be considered.

TRIAL REGISTRATION

UMIN registration in Japan ( UMIN000017758 ) on June 1, 2015. https://www.umin.ac.jp/ctr/index.htm.

The Disorders of Endometrial Receptivity in PCOS and Its Mechanisms

Polycystic ovary syndrome (PCOS) is a mysterious and complicated endocrine disease with the combination of metabolic, reproductive, psychological dysfunctions. Impaired endometrial receptivity and ovulation disorders/anovulation are both important causes of PCOS-related infertility. However, change in endometrium has never received the same attention as ovulatory dysfunction. Besides, putting emphasis on endometrial function may be more realistic for PCOS-related infertility, given the wide use of assisted reproductive technology. The present review focuses on the disorders of endometrial receptivity of patients with PCOS, summarizes the changes of the indicators of endometrial receptivity including leukemia inhibitory factor, homeobox genes A, pinopodes, αvβ3-integrin, and intercellular junctions and also analyzes the possible mechanisms of decreased endometrial receptivity and its relationship with the main endocrine and metabolic disorders of PCOS such as hyperandrogenism, inflammation, insulin resistance, and obesity. Despite several biomarkers have been found to be associated with decreased endometrial receptivity in PCOS, the clinical relevance of these findings still awaits future clarification.