Seminal plasma untargeted metabolomic and lipidomic profiling for the identification of a novel panel of biomarkers and therapeutic targets related to male infertility

Long term exposure to multiple environmental stressors induces mitochondrial dynamics imbalance in testis: Insights from metabolomics and transcriptomics

Long-term exposure to adverse environment stressors (e.g. noise pollution, temperature, and crowding) impaired human health. However, research on the toxic effects of adverse environmental stressors on the male reproductive system is limited. This study employed integrated phenomics, metabolomics, and transcriptomics to investigate physiological disturbances in the testis of mice exposed to multiple adverse environmental stressors for two months. Phenotypic studies indicated that long-term environmental stimuli resulted in significant damage to the blood-testis barrier (BTB) and testes, evidenced by reduced testicular index, disrupted testicular tissue structure, abnormal tight junction protein expression, and spermatozoa abnormalities. Comprehensive multi-omics analysis revealed that long-term exposure to environmental stressors disrupted the BTB and testes, which was associated with mitochondrial metabolism disorders, including oxidative phosphorylation and fatty acid beta-oxidation, as well as glutathione and lipid metabolism alterations. Among these dysregulated pathways, significant alterations were observed in the critical regulators of mitochondrial fusion (MFN2) and fission (DRP1) within the BTB. Specifically, corticosterone treatment decreased tight junction protein expression, increased reactive oxygen species (ROS) levels, and impaired mitochondrial morphology and function, as evidenced by reduced mitochondrial membrane potential, elevated calcium ion concentration, and shortened mitochondrial length and network in vitro. Moreover, inhibiting DRP1 with Mdivi-1 or overexpressing MFN2 mitigated the corticosterone-induced reduction of tight junctions and mitochondrial dysregulation in TM4 cells. Collectively, maintaining mitochondrial homeostasis emerges as a promising strategy to alleviate the BTB and testicular injury induced by long-term exposure to multiple environmental stressors.

Impact of Excess Activin A on the Lipids, Metabolites, and Steroids of Adult Mouse Reproductive Organs

Bioactivity of the hormone and growth factor activin A is central to fertility and health. Dysregulated circulating activin levels occur with medication usage and multiple pathological conditions. The inhibin-alpha knockout mouse (InhaKO) models chronic activin elevation and unopposed activin A bioactivity. In InhaKO fetal testes, lipid droplet, steroid profiles, and seminiferous cords are abnormal; adults develop gonadal and adrenal tumors due to chronic activin A excess exposure. Here we address how this exposure affects lipid, metabolite, and steroid composition in whole testes, ovaries, and adrenals of adult InhaKO mice using histological, transcriptomic, and mass spectrometry (MS) methods, including MS imaging (matrix-assisted laser desorption/ionization-MS imaging). Matrix-assisted laser desorption/ionization-MS imaging delineated spatial lipid profiles within interstitial, inner cord, and outer cord regions containing normal spermatogenesis; these differed between wild-type and KO samples. In proximity to tumors, lipids showed distinctive distribution patterns both within and adjacent to the tumor. Significantly altered lipids and metabolic profiles in whole InhaKO testes homogenates were linked to energy-related pathways. In gonads and adrenal glands of both sexes, steroidogenic enzyme transcription, and steroids are different, as expected. Lipid profiles and steroidogenic enzyme proteins, HSD3B1 and CYP11A1, are affected within and near gonadal tumors. This documents organ-specific effects of chronic activin A elevation on lipid composition and cellular metabolism, in both histologically normal and tumor-affected areas. The potential for activin A to influence numerous steroidogenic processes should be considered in context and with spatial precision, particularly in relationship to pathologies.

Analyzing free fatty acids in seminal plasma from asthenozoospermia patients undergoing antioxidant therapy

OBJECTIVE

Different aspects of the functions of free fatty acid (FFA) in seminal plasma and their implications on male fertility are known. However, the profile of FFA in seminal plasma in asthenozoospermic patients following antioxidant therapy has not been studied.

METHODS

In this case-control study, the total antioxidant capacity (TAC) and FFA profile of the seminal plasma were determined in 80 patients (29 normozoospermic volunteers and 51 asthenozoospermic men) who were treated with antioxidants for three months.

RESULTS

The TAC level in normozoospermic men was significantly higher than in asthenozoospermic men before and after antioxidant therapy with even lower values after the treatment (p=0.0001). The most abundant identified FFAs in seminal plasma were palmitic acid, vaccenic acid, eicosatrienoic acid, stearic acid, and myristoleic acid. Palmitic acid was lower in asthenozoospermic patients (p=0.0001), and antioxidant treatment restored its level to near-control levels. Compared to normozoospermic controls, the level of eicosatrienoic acid is significantly lower in asthenozoospermia patients before (p=0.01) and after treatment (p=0.0001). Additionally, following oral antioxidant supplementation, the FFA pattern in asthenozoospermic patients changes to the pattern observed in normozoospermic men. However, these changes are not statistically significant.

CONCLUSIONS

The TAC level in asthenozoospermic patients after antioxidant treatment did not change to the levels in the control group; it even dropped to a lower level following three months of treatment. Antioxidant treatment can change the level of the FFA compositions of seminal plasma.

Understanding the physiological mechanisms and therapeutic targets of diseases: Lipidomics strategies

As a pivotal branch of metabolomics, lipidomics studies global changes in lipid metabolism under different physiological and pathological conditions or drug interventions, discovers key lipid markers, and elaborates the associated lipid metabolism network. There are a considerable number of lipids in the host, which act on various functional networks such as metabolism and immune regulation. As an indispensable research method, lipidomics plays a key character in the analysis of lipid composition in organisms, the elaboration of the physiological mechanism of lipids, and the decoding of their character in the occurrence and development of diseases by exploring the character of lipids in the host environmental network. As an essential means of driving lipidomics research, High-throughput and High-resolution mass spectrometry is helpful in exploring disease phenotypic characteristics, diagnosing disease biomarkers, regulating related metabolic pathways, and discovering related active components. In this paper, we discuss the specific role of lipidomics in the analysis of disease diagnosis, prognosis and treatment, which is conducive to the realization of accurate and personalized medicine.

Fertility problems in men carrying chromosome 7 inversion: A retrospective, observational study

Infertility is a worldwide public health issue. Fifty percent of infertile couples are male-only. A number of male infertility etiologies are significantly influenced by chromosomal abnormalities. Clinical manifestations, however, differ according to the presence of aberrant chromosomes and distinct breakpoints. The reproductive effects of inversion are evident in those who carry it. The influence of inverted carriers on male infertility may be explained by the interchromosomal effect, although further research is still needed to determine the precise mechanism. Furthermore, selecting clinical reproductive technology presents difficulties for both physician and patients. The aim of this study is to determine the clinical characteristics of 4 males who have an inversion of chromosome 7, and to investigate the connection between the breakpoints of this chromosome and male infertility. For each patient, cytogenetic and semen analyses were carried out. Using PubMed or Online Mendelian Inheritance in Man, relevant research and genes on breakpoints on chromosome 7 were found. This study includes 4 male infertile patients, all of whom had chromosome 7 inversions. 46,XY,inv(7)(p22q22), 46,XY,inv(7)(p21q11.2), 46,XY,inv(7)(p21q21), and 46,XY,inv(7)(p15q36) were the results of the cytogenetic analysis. Three cases of aberrant semen parameters were detected by semen detection. After a literature search, 21 cases of chromosome 7 inversion carriers were found. These carrier couples have varying reproductive histories. Among the 5 cases where semen parameters are available, 1 is azoospermia and 1 is oligoasthenozoospermia. Five significant genes on chromosome 7 have been linked to male infertility. Changes in semen parameters may be connected to the breakpoints 7q11, 7q21, 7q22, and 7q36. Physicians should take into account the relevant breakpoints when offering genetic counseling to patients who have chromosome 7 inversion.

Effect of Seminal Plasma on the Freezability of Boar Sperm

BACKGROUND

Seminal plasma is an important component of semen and has a significant effect on sperm function. However, the relationship between seminal plasma and sperm freezing capacity has not been fully studied.

PURPOSE

Exploring metabolites and proteins related to the boar sperm freezing capacity in seminal plasma, by metabolomic and proteomic approaches, and directly verifying the protective effect of seminal plasma on the cryopreservation of boar sperm using high and low freezability seminal plasma as base freezing extender.

METHODS

Semen samples were collected from 30 different boars, 11 high and 11 low freezing-resistant boars were selected after freezing 2~4 times, and seminal plasma was selected at the same time. Sperm motility and movement parameters were analyzed using a CASA system. Reproductive hormones (Testosterone, progesterone, estradiol, prolactin, prostaglandin F2α, luteinoid hormone) in seminal plasma were detected by ELISA. Analysis of proteins and metabolites in high and low freezing-resistant seminal plasma by proteomics and metabolomics techniques.

RESULTS

The six reproductive hormones tested were not significantly associated with sperm freezing resistance. A total of 13 differentially expressed metabolites (DEMs) and 38 differentially expressed proteins (DEPs) were identified, while a total of 348 metabolites and 1000 proteins were identified. These DEMs were related to energy metabolism, drugs, or environmental pollutants, while the DEPs were mainly involved in the cytoskeletal dynamics and cell adhesion processes. There were 33 metabolites and 70 proteins significantly associated with mean progress motility (PM) at 10 min and 2 h after thawing. The 70 related proteins were associated with cell division and cycle regulation in gene ontology (GO) terms, as well as KEGG pathways, thermogeneration, and pyruvate metabolism. Using highly freezable boar SP as a base freezing extender made no difference from using lowly freezable boar SP, and both were not as good as the commercial control.

CONCLUSION

There were significant differences in seminal plasma with different freezability, but the similarity was much greater than the difference. The protection effect of seminal plasma is not remarkable, and it does not exhibit superior cryoprotective properties compared to commercial semen cryoelongators.

SIGNIFICANCE

This study provides a deeper understanding of how seminal plasma composition affects sperm freezabilty. It provides potential biomarkers and targets for improving sperm cryopreservation techniques.

Proteomics and Metabolomics in Varicocele-Associated Male Infertility: Advancing Precision Diagnostics and Therapy

Background/Objectives: Varicoceles are a common contributor to male infertility, significantly impacting male-factor infertility cases. Traditional diagnostic methods often lack the sensitivity to detect the molecular and cellular disruptions caused by varicoceles, limiting the development of effective, personalized treatments. This narrative review aims to explore the advancements in proteomics and metabolomics as innovative, non-invasive diagnostic tools for varicocele-associated male infertility and their potential in guiding personalized therapeutic strategies. Methods: A comprehensive literature search was conducted using databases such as PubMed, Scopus, and Web of Science up to October 2024. Studies focusing on the application of proteomic and metabolomic analyses in varicocele-associated male infertility were selected. The findings were critically analyzed to synthesize current knowledge and identify future research directions. Results: Proteomic analyses revealed differentially expressed proteins in the sperm and seminal plasma of varicocele patients, revealing disruptions in pathways related to oxidative stress, mitochondrial dysfunction, apoptosis, and energy metabolism. Key proteins such as heat shock proteins, mitochondrial enzymes, and apoptotic regulators were notably altered. Metabolomic profiling uncovered specific metabolites in seminal plasma-such as decreased levels of lysine, valine, and fructose-that correlate with impaired sperm function and fertility potential. The integration of proteomic and metabolomic data provides a comprehensive molecular fingerprint of varicocele-induced infertility, facilitating the identification of novel biomarkers for early diagnosis and the development of personalized therapeutic interventions. Conclusions: Advances in proteomics and metabolomics have significantly enhanced our understanding of the molecular mechanisms underlying varicocele-associated male infertility. These "omics" technologies hold great promise for improving diagnostic accuracy and personalizing treatment, ultimately leading to better outcomes for affected men. Future large-scale clinical trials and validations are essential to confirm these biomarkers and facilitate their integration into routine clinical practice.

Exploring the impact of lipid stress on sperm cytoskeleton: insights and prospects

The decline in male fertility correlates with the global rise in obesity and dyslipidaemia, representing significant public health challenges. High-fat diets induce metabolic alterations, including hypercholesterolaemia, hepatic steatosis and atherosclerosis, with detrimental effects on testicular function. Testicular tissue, critically dependent on lipids for steroidogenesis, is particularly vulnerable to these metabolic disruptions. Excessive lipid accumulation within the testes, including cholesterol, triglycerides and specific fatty acids, disrupts essential sperm production processes such as membrane formation, maturation, energy metabolism and cell signalling. This leads to apoptosis, impaired spermatogenesis, and abnormal sperm morphology and function, ultimately compromising male fertility. During spermiogenesis, round spermatids undergo extensive reorganization, including the formation of the acrosome, manchette and specialized filamentous structures, which are essential for defining the final sperm cell shape. In this Perspective, we examine the impact of high-fat diets on the cytoskeleton of spermatogenic cells and its consequences to identify the mechanisms underlying male infertility associated with dyslipidaemia. Understanding these processes may facilitate the development of therapeutic strategies, such as dietary interventions or natural product supplementation, that aim to address infertility in men with obesity and hypercholesterolaemia. The investigation of cytoskeleton response to lipid stress extends beyond male reproduction, offering insights with broader implications.

Revisiting the Injury Mechanism of Goat Sperm Caused by the Cryopreservation Process from a Perspective of Sperm Metabolite Profiles

Semen cryopreservation results in the differential remodeling of the molecules presented in sperm, and these alterations related to reductions in sperm quality and its physiological function have not been fully understood. Given this, this study aimed to investigate the cryoinjury mechanism of goat sperm by analyzing changes of the metabolic characteristics in sperm during the cryopreservation process. The ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS) technique was performed to explore metabolite profiles of fresh sperm (C group), equilibrated sperm (E group), and frozen-thawed sperm (F group). In total, 2570 metabolites in positive mode and 2306 metabolites in negative mode were identified, respectively. After comparative analyses among these three groups, 374 differentially abundant metabolites (DAMs) in C vs. E, 291 DAMs in C vs. F, and 189 DAMs in E vs. F were obtained in the positive mode; concurrently, 530 DAMs in C vs. E, 405 DAMs in C vs. F, and 193 DAMs in E vs. F were obtained in the negative mode, respectively. The DAMs were significantly enriched in various metabolic pathways, including 31 pathways in C vs. E, 25 pathways in C vs. F, and 28 pathways in E vs. F, respectively. Among them, 65 DAMs and 25 significantly enriched pathways across the three comparisons were discovered, which may be tightly associated with sperm characteristics and function. Particularly, the functional terms such as TCA cycle, biosynthesis of unsaturated fatty acids, sphingolipid metabolism, glycine, serine and threonine metabolism, alpha-linolenic acid metabolism, and pyruvate metabolism, as well as associated pivotal metabolites like ceramide, betaine, choline, fumaric acid, L-malic acid and L-lactic acid, were focused on. In conclusion, our research characterizes the composition of metabolites in goat sperm and their alterations induced by the cryopreservation process, offering a critical foundation for further exploring the molecular mechanisms of metabolism influencing the quality and freezing tolerance of goat sperm. Additionally, the impacts of equilibration at low temperature on sperm quality may need more attentions as compared to the freezing and thawing process.

Male infertility risk and plasma lipidome: a Mendelian randomization study

Background

In recent years, the decline in sperm quality in men has become a global trend. There is a close relationship between sperm quality and pregnancy outcome. There is a large body of literature supporting the role of plasma lipidome in male infertility, while the complex mechanisms between them and male infertility are still less clear. Systematic study of the causal relationship between plasma lipidome and MI can help to provide new therapeutic ideas and targets for male infertility.

Methods

In this study, we used a two-sample Mendelian randomization analysis based on Genome-wide association studies pooled data of 179 causal relationships between plasma lipidome and male infertility. We used employed the inverse variance weighted method as the main analysis to assess causality between exposure and outcome, in addition to MR-Egger, Weighted median as complementary methods, and tests for multiplicity and heterogeneity.

Results

We identified 13 plasma lipidome comprising 4 types of plasma lipidome that were associated with male infertility. Among these, 9 plasma lipidome were found to be protective factors, while 4 were risk factors. Notably, the largest proportion of these plasma lipidome were triglyceride types, with Sphingomyelin (d40:1) exhibiting the strongest association with male infertility.

Conclusion

These findings contribute to the current better understanding of male infertility and provide new perspectives on the underlying etiology of male infertility as well as prevention and treatment strategies. In addition, clinical trial validation is needed to assess the potential of these plasma lipidome as biomarkers.

Lipidomics random forest algorithm of seminal plasma is a promising method for enhancing the diagnosis of necrozoospermia

BACKGROUND

Despite the clear clinical diagnostic criteria for necrozoospermia in andrology, the fundamental mechanisms underlying it remain elusive. This study aims to profile the lipid composition in seminal plasma systematically and to ascertain the potential of lipid biomarkers in the accurate diagnosis of necrozoospermia. It also evaluates the efficacy of a lipidomics-based random forest algorithm model in identifying necrozoospermia.

METHODS

Seminal plasma samples were collected from patients diagnosed with necrozoospermia (n = 28) and normozoospermia (n = 28). Liquid chromatography-mass spectrometry (LC-MS) was used to perform lipidomic analysis and identify the underlying biomarkers. A lipid functional enrichment analysis was conducted using the LION lipid ontology database. The top 100 differentially significant lipids were subjected to lipid biomarker examination through random forest machine learning model.

RESULTS

Lipidomic analysis identified 46 lipid classes comprising 1267 lipid metabolites in seminal plasma. The top five enriched lipid functions as follows: fatty acid (FA) with ≤ 18 carbons, FA with 16-18 carbons, monounsaturated FA, FA with 18 carbons, and FA with 16 carbons. The top 100 differentially significant lipids were subjected to machine learning analysis and identified 20 feature lipids. The random forest model identified lipids with an area under the curve > 0.8, including LPE(20:4) and TG(4:0_14:1_16:0).

CONCLUSIONS

LPE(20:4) and TG(4:0_14:1_16:0), were identified as differential lipids for necrozoospermia. Seminal plasma lipidomic analysis could provide valuable biochemical information for the diagnosis of necrozoospermia, and its combination with conventional sperm analysis may improve the accuracy and reliability of the diagnosis.

The Role of One-Carbon Metabolism and Methyl Donors in Medically Assisted Reproduction: A Narrative Review of the Literature

One-carbon (1-C) metabolic deficiency impairs homeostasis, driving disease development, including infertility. It is of importance to summarize the current evidence regarding the clinical utility of 1-C metabolism-related biomolecules and methyl donors, namely, folate, betaine, choline, vitamin B12, homocysteine (Hcy), and zinc, as potential biomarkers, dietary supplements, and culture media supplements in the context of medically assisted reproduction (MAR). A narrative review of the literature was conducted in the PubMed/Medline database. Diet, ageing, and the endocrine milieu of individuals affect both 1-C metabolism and fertility status. In vitro fertilization (IVF) techniques, and culture conditions in particular, have a direct impact on 1-C metabolic activity in gametes and embryos. Critical analysis indicated that zinc supplementation in cryopreservation media may be a promising approach to reducing oxidative damage, while female serum homocysteine levels may be employed as a possible biomarker for predicting IVF outcomes. Nonetheless, the level of evidence is low, and future studies are needed to verify these data. One-carbon metabolism-related processes, including redox defense and epigenetic regulation, may be compromised in IVF-derived embryos. The study of 1-C metabolism may lead the way towards improving MAR efficiency and safety and ensuring the lifelong health of MAR infants.

An integrated metabo-lipidomics profile of induced sputum for the identification of novel biomarkers in the differential diagnosis of asthma and COPD

BACKGROUND

Due to their complexity and to the presence of common clinical features, differentiation between asthma and chronic obstructive pulmonary disease (COPD) can be a challenging task, complicated in such cases also by asthma-COPD overlap syndrome. The distinct immune/inflammatory and structural substrates of COPD and asthma are responsible for significant differences in the responses to standard pharmacologic treatments. Therefore, an accurate diagnosis is of central relevance to assure the appropriate therapeutic intervention in order to achieve safe and effective patient care. Induced sputum (IS) accurately mirrors inflammation in the airways, providing a more direct picture of lung cell metabolism in comparison to those specimen that reflect analytes in the systemic circulation.

METHODS

An integrated untargeted metabolomics and lipidomics analysis was performed in IS of asthmatic (n = 15) and COPD (n = 22) patients based on Ultra-High-Pressure Liquid Chromatography-Mass Spectrometry (UHPLC-MS) and UHPLC-tandem MS (UHPLC-MS/MS). Partial Least Squares-Discriminant Analysis (PLS-DA) was applied to resulting dataset. The analysis of main enriched metabolic pathways and the association of the preliminary metabolites/lipids pattern identified to clinical parameters of asthma/COPD differentiation were explored. Multivariate ROC analysis was performed in order to determine the discriminatory power and the reliability of the putative biomarkers for diagnosis between COPD and asthma.

RESULTS

PLS-DA indicated a clear separation between COPD and asthmatic patients. Among the 15 selected candidate biomarkers based on Variable Importance in Projection scores, putrescine showed the highest score. A differential IS bio-signature of 22 metabolites and lipids was found, which showed statistically significant variations between asthma and COPD. Of these 22 compounds, 18 were decreased and 4 increased in COPD compared to asthmatic patients. The IS levels of Phosphatidylethanolamine (PE) (34:1), Phosphatidylglycerol (PG) (18:1;18:2) and spermine were significantly higher in asthmatic subjects compared to COPD.

CONCLUSIONS

This is the first pilot study to analyse the IS metabolomics/lipidomics signatures relevant in discriminating asthma vs COPD. The role of polyamines, of 6-Hydroxykynurenic acid and of D-rhamnose as well as of other important players related to the alteration of glycerophospholipid, aminoacid/biotin and energy metabolism provided the construction of a diagnostic model that, if validated on a larger prospective cohort, might be used to rapidly and accurately discriminate asthma from COPD.

Metabolomics of male infertility

This review explores the use of metabolomics in male infertility. Metabolomics, an evolving omics technology that targets the products of cellular metabolism, is valuable for elucidating underlying pathophysiology of many disorders including male infertility. The identification of reliable biomarkers is essential for accurate diagnosis and for developing precision therapeutics for those afflicted by reproductive dysfunction. Unfortunately, despite significant progress to date, the intricate relationships between these metabolic pathways and male infertility remain elusive. It is clear, however, that additional research is required to more fully characterize the role of metabolomics in this disorder and in the potential development of targeted therapies for precision medicine.