Association between seminal plasma zinc level and asthenozoospermia: a meta-analysis study

Understanding seminal plasma in male infertility: emerging markers and their implications

Infertility affects a significant proportion of the reproductive-aged population, with male-associated factors contributing to over half of the cases. However, current diagnostic tools have limitations, leading to an underestimation of the true prevalence of male infertility. While traditional semen parameters provide some insights, they fail to determine the true fertility potential in a substantial number of instances. Therefore, it is crucial to investigate additional molecular targets responsible for male infertility to improve understanding and identification of such cases. Seminal plasma, the main carrier of molecules derived from male reproductive glands, plays a crucial role in reproduction. Amongst its multifarious functions, it regulates processes such as sperm capacitation, sperm protection and maturation, and even interaction with the egg's zona pellucida. Seminal plasma offers a non-invasive sample for urogenital diagnostics and has shown promise in identifying biomarkers associated with male reproductive disorders. This review aims to provide an updated and comprehensive overview of seminal plasma in the diagnosis of male infertility, exploring its composition, function, methods used for analysis, and the application of emerging markers. Apart from the application, the potential challenges of seminal plasma analysis such as standardisation, marker interpretation and confounding factors have also been addressed. Moreover, we have also explored future avenues for enhancing its utility and its role in improving diagnostic strategies. Through comprehensive exploration of seminal plasma's diagnostic potential, the present analysis seeks to advance the understanding of male infertility and its effective management.

Small noncoding RNAs and sperm nuclear basic proteins reflect the environmental impact on germ cells

BACKGROUND

Molecular techniques can complement conventional spermiogram analyses to provide new information on the fertilizing potential of spermatozoa and to identify early alterations due to environmental pollution.

METHODS

Here, we present a multilevel molecular profiling by small RNA sequencing and sperm nuclear basic protein analysis of male germ cells from 33 healthy young subjects residing in low and high-polluted areas.

RESULTS

Although sperm motility and sperm concentration were comparable between samples from the two sites, those from the high-pollution area had a higher concentration of immature/immune cells, a lower protamine/histone ratio, a reduced ability of sperm nuclear basic proteins to protect DNA from oxidative damage, and an altered copper/zinc ratio in sperm. Sperm levels of 32 microRNAs involved in intraflagellar transport, oxidative stress response, and spermatogenesis were different between the two areas. In parallel, a decrease of Piwi-interacting RNA levels was observed in samples from the high-polluted area.

CONCLUSIONS

This comprehensive analysis provides new insights into pollution-driven epigenetic alterations in sperm not detectable by spermiogram.

Correlation of zinc level in spermoplasm with fertility characteristics of human ejaculate

Background: Zinc is essential for the normal functioning of the male reproductive system. The data on the diagnostic value of the determination of zinc in human spermoplasm and the relationship of its level with the main parameters of sperm fertility are contradictory. Aims: Study of correlations of zinc level in spermoplasm with spermogram characteristics. Methods: Sperm of men of reproductive age (n=486, average age 33.073.03 years) was studied. In addition to the standard spermogram, MAR tests (IgA, IgG and IgM) were performed in the sperm samples, the degree of fragmentation of sperm DNA was assessed, the interaction of sperm with hyaluronic acid was assessed, acrosine activity, neutral alpha-glucosidase activity was determined, citric acid, fructose and glycodelin levels were determined, the level of reactive oxygen species was studied. Determination of the zinc level in the spermoplasm was carried out by a standard spectrophotometric method with 5-Br-PAPS chromogen. Pearson's formula was used for correlation analysis. The study was conducted from 2018 to May 2022, once. Results: A significant negative correlation of the zinc level in the spermoplasm with the age of men was revealed (r=-0.1625, p0.001). The level of zinc in the spermoplasm was weakly negatively correlated with the dilution time and with the viscosity of the sperm. The positive correlation was with the number of spermatozoa (r=0.1345, p0.01) and their mobility (r=0.3825, p0.00001). The level of zinc in the spermoplasm negatively correlates with the degree of fragmentation of sperm DNA and with the amount of reactive oxygen species, and with the test for binding of sperm with hyaluronic acid positively. Conclusions: The level of zinc in the spermoplasm significantly correlates with a number of physiological and biochemical characteristics of sperm. The data obtained allow us to recommend the determination of zinc in the sperm plasma not only to assess the functional activity of the prostate gland, but also to diagnose the fertility of the ejaculate, as well as to optimize therapy with zinc-containing drugs and improve control over the effectiveness of the treatment.

Analytical Evaluation of Wet and Dry Mechanochemical Syntheses of Calcium-Deficient Hydroxyapatite Containing Zinc Using X-ray Diffractometry and Near-Infrared Spectroscopy

Calcium-deficient zinc-containing calcium phosphate (ZnAP), which has sustained zinc release properties that are effective for treating osteoporosis, can be efficiently synthesized as a biomaterial through wet grinding. To elucidate the physicochemical mechanism of these mechanochemical syntheses, ground products were obtained from the starting material powder (S-CP), consisting of calcium hydrogen phosphate dihydrate (CHPD), calcium oxide (CaO), and zinc oxide (ZnO), by wet and dry grinding for 0–3 h in a centrifugal ball mill. The ground S-CP products were analyzed using powder X-ray diffraction (XRD) and near-infrared spectroscopy (NIRS); the crystal transformations and molecular interactions of the ground products were kinetically analyzed. The XRD and second-derivative NIRS results indicate that the S-CP is primarily transformed into ZnAP via amorphous solid formation in wet grinding, and the reaction follows a consecutive reaction model. In contrast, in dry grinding, the ground product of CHPD and CaO is transformed into an amorphous solid following an equilibrium reaction model; however, ZnO is predominantly not transformed and remains crystalline.

An Overview of Essential Microelements and Common Metallic Nanoparticles and Their Effects on Male Fertility

Numerous factors affect reproduction, including stress, diet, obesity, the use of stimulants, or exposure to toxins, along with heavy elements (lead, silver, cadmium, uranium, vanadium, mercury, arsenic). Metals, like other xenotoxins, can cause infertility through, e.g., impairment of endocrine function and gametogenesis or excess production of reactive oxygen species (ROS). The advancement of nanotechnology has created another hazard to human safety through exposure to metals in the form of nanomaterials (NMs). Nanoparticles (NPs) exhibit a specific ability to penetrate cell membranes and biological barriers in the human body. These ultra-fine particles (<100 nm) can enter the human body through the respiratory tract, food, skin, injection, or implantation. Once absorbed, NPs are transported to various organs through the blood or lymph. Absorbed NPs, thanks to ultrahigh reactivity compared to bulk materials in microscale size, disrupt the homeostasis of the body as a result of interaction with biological molecules such as DNA, lipids, and proteins; interfering with the functioning of cells, organs, and physiological systems; and leading to severe pathological dysfunctions. Over the past decades, much research has been performed on the reproductive effects of essential trace elements. The research hypothesis that disturbances in the metabolism of trace elements are one of the many causes of infertility has been unquestionably confirmed. This review examines the complex reproductive risks for men regarding the exposure to potentially harmless xenobiotics based on a series of 298 articles over the past 30 years. The research was conducted using PubMed, Web of Science, and Scopus databases searching for papers devoted to in vivo and in vitro studies related to the influence of essential elements (iron, selenium, manganese, cobalt, zinc, copper, and molybdenum) and widely used metallic NPs on male reproduction potential.

Heterogeneous Immunolocalisation of Zinc Transporters ZIP6, ZIP10 and ZIP14 in Human Normo- and Asthenozoospermic Spermatozoa

Zinc (in the form of Zn²⁺) is necessary for male fertility. Both Zn²⁺ quantity and its localisation have been detected in seminal plasma and ejaculated spermatozoa, suggesting its active uptake via zinc import transporters (ZIPs). Immunofluorescence was used to characterise the expression and localisation of three distinct types of ZIP transporters in ejaculated spermatozoa of normo- and asthenozoospermic sperm samples. ZIP6, ZIP10 and ZIP14 showed heterogeneous sperm cell expression and different compartmental distribution. In both types of sperm samples, ZIP6 and ZIP14 were predominantly localised in the sperm head, while ZIP10 was found along the sperm tail. Compartmental localisation of ZIPs in asthenozoospermia was not changed. However, regarding sub-compartmental localisation in sperm head regions, for ZIP6 asthenozoospermia only decreased its acorn/crescent-like pattern. In contrast, ZIP14 immunostaining was altered in favour of crescent-like, as opposed to acorn-like and acorn/crescent-like patterns. The specific ZIPs localisation may reflect their different roles in sperm cell integrity and motility and may change over time. This is the first report of their specific compartmental and sub-compartmental localisation in ejaculated human sperm cells. Further research will lead to a greater understanding of the roles of ZIPs in sperm cell biology, which could positively influence procedures for human infertility therapy.

Impact of seminal and serum zinc on semen quality and hormonal status: A population-based cohort study of Russian young men

BACKGROUND

Trace elements are important factors in human reproductive health. Among them, special attention is paid to zinc, which is an essential trace element and is necessary for the normal functioning of the male reproductive system and the process of spermatogenesis. The aim of the study was to investigate the association between seminal and serum zinc concentrations and semen quality and reproductive hormone levels in population of Russian young men.

METHODS

The study population consisted of 626 young Russian men (median age 22.5 years), recruited from the general population, regardless of their fertility status. Each participant provided semen and blood sample, information about his lifestyle and ethnicity. Semen quality (sperm concentration, motility and morphology), reproductive hormone levels (testosterone, estradiol, LH, FSH and inhibin B), and serum and seminal zinc concentrations were evaluated. The semen samples were analyzed according to the WHO laboratory manual (WHO, 2010). Serum hormones were measured by enzyme immunoassay, zinc concentrations were determined using spectrophotometry and direct colorimetry without deproteinization.

RESULTS

Zinc was present in the seminal plasma in a significantly higher concentration than in the blood serum (median serum Zn concentration was 23.6 μmol/L vs seminal Zn concentration 1571.8 μmol/L). The seminal zinc concentration was positively related to the total sperm count, sperm concentration, progressive motility and normal morphology (Spearman's test: 0.221; 0.286; 0.269; 0.183, respectively, p < 0.001), while the serum Zn concentration was negatively related to serum testosterone and estradiol levels (r = -0.249 and r = -0.096, respectively, p < 0.001-0.05). It was found that the seminal Zn content in men with normal semen quality was higher compared to men with lowered semen quality (means: 6.37 and 5.03 μmol/ejaculate, respectively, p < 0.001). Similarly, the semen volume, total sperm count, sperm concentration, progressive motility, normal morphology and the serum testosterone level in men with the seminal Zn deficiency were lower than in men with the normal seminal Zn content.

CONCLUSION

Based on the results of our population-based study, seminal Zn levels were closely associated with semen parameters in young men, so Zn deficiency may be an important risk factor for lowered semen quality. Seminal Zn determinations should be considered as a useful tool in addition to other parameters in assessing male fertility.

Diabetes Mellitus Causes Male Reproductive Dysfunction: A Review of the Evidence and Mechanisms

The metabolic disorders caused by diabetes can lead to various complications, including dysfunction of the male reproductive system. In patients with diabetes, long-term hyperglycemia results in diabetic vascular neuropathy, oxidative stress injury, abnormal zinc metabolism, and insulin resistance syndrome. In addition, insulin deficiency and resistance in diabetes can damage the hypothalamus, pituitary gland, gonads, and perigonads. This can reduce the secretion of sex hormones including gonadotropin-releasing hormone, follicle stimulating hormone, luteinizing hormone, and testosterone, and can lead to testicular atrophy, stromal cell atrophy, seminiferous tubule damage, spermatogenic cell damage, and other structural injuries of the male reproductive organs. These actions can affect male fertility and reproductive health. Herein, we review studies that report a causative role of diabetes in male reproductive function. We also discuss the evidence-based mechanisms involved in the processes of diabetes-related male sexual and reproductive dysfunction as well as the progress in treatment.

Zinc

Since the discovery of manifest Zn deficiency in 1961, the increasing number of studies demonstrated the association between altered Zn status and multiple diseases. In this chapter, we provide a review of the most recent advances on the role of Zn in health and disease (2010-20), with a special focus on the role of Zn in neurodegenerative and neurodevelopmental disorders, diabetes and obesity, male and female reproduction, as well as COVID-19. In parallel with the revealed tight association between ASD risk and severity and Zn status, the particular mechanisms linking Zn2+ and ASD pathogenesis like modulation of synaptic plasticity through ProSAP/Shank scaffold, neurotransmitter metabolism, and gut microbiota, have been elucidated. The increasing body of data indicate the potential involvement of Zn2+ metabolism in neurodegeneration. Systemic Zn levels in Alzheimer's and Parkinson's disease were found to be reduced, whereas its sequestration in brain may result in modulation of amyloid β and α-synuclein processing with subsequent toxic effects. Zn2+ was shown to possess adipotropic effects through the role of zinc transporters, zinc finger proteins, and Zn-α2-glycoprotein in adipose tissue physiology, underlying its particular role in pathogenesis of obesity and diabetes mellitus type 2. Recent findings also contribute to further understanding of the role of Zn2+ in spermatogenesis and sperm functioning, as well as oocyte development and fertilization. Finally, Zn2+ was shown to be the potential adjuvant therapy in management of novel coronavirus infection (COVID-19), underlining the perspectives of zinc in management of old and new threats.

The effect of iron and/or zinc diet supplementation and termination of this practice on the antioxidant status of the reproductive tissues and sperm viability in rats

AIMS

The aim of this study was to investigate the effect of iron or/and zinc supplementation and termination of this treatment on the antioxidant defence of the male reproductive system and sperm viability in rats.

METHODS

The study consisted of 3 stages: I) 4-week adaptation to the diets (C-control or D-iron deficient); II) 4-week iron and/or zinc supplementation (10-times more than in the C diet of iron: CSFe, DSFe; zinc: CSZn, DSZn; or iron and zinc: CSFeZn, DSFeZn; and III) 2-week post-supplementation period (the same diets as during stage I). Parameters of antioxidant status (total antioxidant capacity and SOD, GPx, and CAT activiy), oxidative damage (lipid and protein peroxidation), and sperm viability were measured.

RESULTS

Simultaneous iron and zinc supplementation compared to iron supplementation (CSFeZn vs CSFe) increased SOD activity in the testes and decreased the level of malondialdehyde in the epididymis after stage II, and increased the percentage of live sperm after stage III. After discontinuation of the iron and zinc supplementation and a return to the control diet, the following was observed a decrease of SOD activity in the testes and GPx activity in the epididymis, and a increase malondialdehyde concentration in prostates. After stage III, in DSFeZn vs DSFe rats, an increase of SOD and CAT activity in the epididymis was found.

CONCLUSION

Zinc supplementation simultaneous with iron may protect the male reproductive system against oxidative damage induced by high doses of iron and may have a beneficial effect on sperm viability. The effect of this supplementation was observed even two weeks after the termination of the intervention.

Putative human sperm Interactome: a networks study

Background

For over sixty years, it has been known that mammalian spermatozoa immediately after ejaculation are virtually infertile. They became able to fertilize only after they reside for long time (hours to days) within female genital tract where they complete their functional maturation, the capacitation. This process is finely regulated by the interaction with the female environment and involves, in spermatozoa, a myriad of molecules as messengers and target of signals. Since, to date, a model able to represent the molecular interaction that characterize sperm physiology does not exist, we realized the Human Sperm Interactme Network3.0 (HSIN3.0) and its main component (HSNI3.0_MC), starting from the pathway active in male germ cells.

Results

HSIN3.0 and HSIN3.0_MC are scale free networks, adherent to the Barabasi-Albert model, and are characterised by an ultra-small world topology. We found that they are resistant to random attacks and that are designed to respond quickly and specifically to external inputs. In addition, it has been possible to identify the most connected nodes (the hubs) and the bottlenecks nodes. This result allowed us to explore the control mechanisms active in driving sperm biochemical machinery and to verify the different levels of controls: party vs. date hubs and hubs vs. bottlenecks, thanks the availability of data from KO mice. Finally, we found that several key nodes represent molecules specifically involved in function that are thought to be not present or not active in sperm cells, such as control of cell cycle, proteins synthesis, nuclear trafficking, and immune response, thus potentially open new perspectives on the study of sperm biology.

Conclusions

For the first time we present a network representing putative human sperm interactome. This result gives very intriguing biological information and could contribute to the knowledge of spermatozoa, either in physiological or pathological conditions.

Electronic supplementary material

The online version of this article (10.1186/s12918-018-0578-6) contains supplementary material, which is available to authorized users.

Seminal biomarkers for the evaluation of male infertility

For men struggling to conceive with their partners, diagnostic tools are limited and often consist of only a standard semen analysis. This baseline test serves as a crude estimation of male fertility, leaving patients and clinicians in need of additional diagnostic biomarkers. Seminal fluid contains the highest concentration of molecules from the male reproductive glands, therefore, this review focuses on current and novel seminal biomarkers in certain male infertility scenarios, including natural fertility, differentiating azoospermia etiologies, and predicting assisted reproductive technique success. Currently available tests include antisperm antibody assays, DNA fragmentation index, sperm fluorescence in situ hybridization, and other historical sperm functional tests. The poor diagnostic ability of current assays has led to continued efforts to find more predictive biomarkers. Emerging research in the fields of genomics, epigenetics, proteomics, transcriptomics, and metabolomics holds promise for the development of novel male infertility biomarkers. Seminal protein-based assays of TEX101, ECM1, and ACRV1 are already available or under final development for clinical use. Additional panels of DNA, RNA, proteins, or metabolites are being explored as we attempt to understand the pathophysiologic processes of male infertility. Future ventures will need to continue data integration and validation for the development of clinically useful infertility biomarkers to aid in male infertility diagnosis, treatment, and counseling.