Role of Oxidative Stress in Male Infertility: An Updated Review

Effect of seminal redox status on lipid peroxidation, apoptosis and DNA fragmentation in spermatozoa of infertile Saudi males

Objectives:

To assess the effect of seminal redox status on lipid peroxidation (LPO), apoptosis and integrity of sperm DNA in infertile males.

Methods:

In this case-control study, the total antioxidant status (TAS) and reactive oxygen species (ROS) levels were analyzed within the seminal plasma of fertile normozoospermic, n=40 and infertile (asthenozoospermic, n=30; oligoasthenoteratozoospermic, n=30) males. Additionally, the level of 4-hydroxynonenal (4-HNE), DNA fragmentation, and caspase-3 activity were estimated in the spermatozoa.

Results:

Significantly (p<0.001) increased seminal ROS level with decreased TAS scores was observed in the infertile groups compared to normozoospermics. The infertile males showed marked elevated (p<0.001) levels of 4-HNE, DNA fragmentation and caspase-3 activity compared to normozoospermics, which was positively correlated to increased seminal ROS levels and negatively to the TAS score in the studied groups. Seminal ROS level was significantly inverse correlated to the semen parameters. Additionally, a strong negative correlation between DNA fragmentation, LPO, caspase-3activity and seminal parameters were observed.

Conclusion:

Seminal oxidative stress is a potential risk factor for LPO, DNA damage, and apoptosis in spermatozoa, which can affect semen quality and male fertility. Thus, in addition to conventional seminological parameters, measurement of seminal oxidative stress and sperm DNA integrity may also be employed to investigate the functional integrity of spermatozoa at the molecular level.

Viral pathogenesis of SARS-CoV-2 infection and male reproductive health

Coronavirus disease 2019 (COVID-19) has emerged as a new public health crisis, threatening almost all aspects of human life. Originating in bats, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is transmitted to humans through unknown intermediate hosts, where it is primarily known to cause pneumonia-like complications in the respiratory system. Organ-to-organ transmission has not been ruled out, thereby raising the possibility of the impact of SARS-CoV-2 infection on multiple organ systems. The male reproductive system has been hypothesized to be a potential target of SARS-CoV-2 infection, which is supported by some preliminary evidence. This may pose a global threat to male fertility potential, as men are more prone to SARS-CoV-2 infection than women, especially those of reproductive age. Preliminary reports have also indicated the possibility of sexual transmission of SARS-CoV-2. It may cause severe complications in infected couples. This review focuses on the pathophysiology of potential SARS-CoV-2 infection in the reproductive organs of males along with their invasion mechanisms. The risks of COVID-19 on male fertility as well as the differences in vulnerability to SARS-CoV-2 infection compared with females have also been highlighted.

The protective effect of Kombucha against silver nanoparticles-induced toxicity on testicular tissue in NMRI mice

Silver nanoparticles (SNPs) can pass from the cell membrane and testicular blood barrier due to their small size, and by increasing oxidative stress they cause disorder in the male reproductive system. Kombucha is a traditional fermented drink with detoxification and potent antioxidant properties. We aimed to examine the protective effect of Kombucha against the damages due to SNPs on the testis tissue. In this experimental study, NMRI mice were randomly separated into four groups (n = 6), namely control (distilled water), SNPs (500 mg/kg), Kombucha extract (9 ml/kg) and SNPs + Kombucha, and were treated with gavage for 35 days. A significant decrease in testosterone level and total antioxidant capacity, and a significant increase in malondialdehyde concentration was observed in the SNPs group in comparison with the control group. Histological studies on the testis of mice treated with SNPs showed vacuolation, decrease in generational epithelium thickness, seminiferous tubules diameter, testis volume and the number of spermatozoa in lumen of the seminiferous tubule and increase in the volume of interstitial space while the mentioned parameters were improved in the SNPs + Kombucha group compared to the SNPs group. Kombucha reduces the adverse effects of SNPs on testis tissue and improves the function of the male reproductive system.

Collapsed mitochondrial cristae in goat spermatozoa due to mercury result in lethality and compromised motility along with altered kinematic patterns

Earlier we have reported mercury-induced alterations in functional dynamics of buck spermatozoa through free radicals-mediated oxidative stress and spontaneous acrosome reaction. Based on our earlier findings, we aimed to investigate the effect of mercury exposure on motility, kinematic patterns, DNA damage, apoptosis and ultra-structural alterations in goat spermatozoa following in vitro exposure to different concentrations (0.031-1.25 µg/ml) of mercuric chloride for 15 min and 3 h. Following exposure of sperm cells to 0.031 µg/ml of mercuric chloride for 3 h, livability and motility of sperms was significantly reduced along with altered kinematic patterns, significant increase in per cent necrotic sperm cells and number of cells showing DNA damage; and this effect was dose- and time-dependent. Contrary to up-regulation of Bax gene after 3 h in control group, there was significant increase in expression of Bcl-2 in mercury-treated groups. Transmission electron microscopy studies revealed rifts and nicks in plasma and acrosomal membrane, mitochondrial sheath, and collapsed mitochondria with loss of helical organization of mitochondria in the middle piece of spermatozoa. Our findings evidently suggest that mercury induces necrosis instead of apoptosis and targets the membrane, acrosome, mid piece of sperms; and the damage to mitochondria seems to be responsible for alterations in functional and kinematic attributes of spermatozoa.

Improvement Effect of Metformin on Female and Male Reproduction in Endocrine Pathologies and Its Mechanisms

Metformin (MF), a first-line drug to treat type 2 diabetes mellitus (T2DM), alone and in combination with other drugs, restores the ovarian function in women with polycystic ovary syndrome (PCOS) and improves fetal development, pregnancy outcomes and offspring health in gestational diabetes mellitus (GDM) and T2DM. MF treatment is demonstrated to improve the efficiency of in vitro fertilization and is considered a supplementary drug in assisted reproductive technologies. MF administration shows positive effect on steroidogenesis and spermatogenesis in men with metabolic disorders, thus MF treatment indicates prospective use for improvement of male reproductive functions and fertility. MF lacks teratogenic effects and has positive health effect in newborns. The review is focused on use of MF therapy for restoration of female and male reproductive functions and improvement of pregnancy outcomes in metabolic and endocrine disorders. The mechanisms of MF action are discussed, including normalization of metabolic and hormonal status in PCOS, GDM, T2DM and metabolic syndrome and restoration of functional activity and hormonal regulation of the gonadal axis.

Lack of trusted diagnostic tools for undetermined male infertility

Semen analysis is the cornerstone of evaluating male infertility, but it is imperfect and insufficient to diagnose male infertility. As a result, about 20% of infertile males have undetermined infertility, a term encompassing male infertility with an unknown underlying cause. Undetermined male infertility includes two categories: (i) idiopathic male infertility-infertile males with abnormal semen analyses with an unknown cause for that abnormality and (ii) unexplained male infertility-males with "normal" semen analyses who are unable to impregnate due to unknown causes. The treatment of males with undetermined infertility is limited due to a lack of understanding the frequency of general sperm defects (e.g., number, motility, shape, viability). Furthermore, there is a lack of trusted, quantitative, and predictive diagnostic tests that look inside the sperm to quantify defects such as DNA damage, RNA abnormalities, centriole dysfunction, or reactive oxygen species to discover the underlying cause. To better treat undetermined male infertility, further research is needed on the frequency of sperm defects and reliable diagnostic tools that assess intracellular sperm components must be developed. The purpose of this review is to uniquely create a paradigm of thought regarding categories of male infertility based on intracellular and extracellular features of semen and sperm, explore the prevalence of the various categories of male factor infertility, call attention to the lack of standardization and universal application of advanced sperm testing techniques beyond semen analysis, and clarify the limitations of standard semen analysis. We also call attention to the variability in definitions and consider the benefits towards undetermined male infertility if these gaps in research are filled.

Waterpipe Tobacco Smoke Exposure during Lactation-Susceptibility of Reproductive Hormones and Oxidative Stress Parameters in Male Progeny Rats

There is a growing evidence for the public health hazards associated with waterpipe tobacco smoking (WTS). While the adverse effects of WTS exposure during pregnancy on the offspring are widely reported, its impact during breastfeeding remains less understood. The effects of WTS exposure during lactation on the reproductive hormones and oxidative stress biomarkers of adult male progeny were examined. Lactating rats received either fresh air (controls) or mainstream WTS for 1 h twice/day from day 4 to day 21 of lactation. The offspring was then followed up until week 20. The data indicated that WTS exposure in the lactating animals reduced the levels of follicle-stimulating hormone (FSH), prolactin (P < 0.05), luteinizing hormone (LH) (P = 0.1146), and estradiol (P = 0.0773) in the blood in male progeny. While the activities of testicular superoxide dismutase (SOD), glutathione peroxidase (GPx) and the levels of thiobarbituric acid reactive substances (TBARS) and blood levels of testosterone (P >0.05) remained unaltered, the activity of catalase increased significantly indicating an increased oxidant load in the WTS exposed rats compared to the controls. WTS exposure during lactation impairs male reproductive hormonal profile, augments oxidative damage, and potentially affects male fertility in male offspring rats.

Systematic Review and Critical Analysis on Dietary Supplements for Male Infertility: From a Blend of Ingredients to a Rationale Strategy

CONTENT

Dietary supplements (DS) for male infertility marketed in Italy were evaluated for composition, concentration of ingredients, and recommended daily dose. A systematic review of literature identified ingredients potentially effective on sperm parameters and their minimal effective daily dose (mED).

OBJECTIVE

This study was conducted in order to critically evaluate the composition and efficacy of DS marketed in Italy.

DESIGN SETTING AND PARTICIPANTS

This was a systematic review of randomized controlled trials.

EVIDENCE ACQUISITION

A formula allowed us to classify the expected efficacy of each DS, based on composition. Each DS was scored and included into three classes of expected efficacy: high, low, and none.

EVIDENCE SYNTHESIS

Among 24 supplements, 3 (12.5%) fall in high, 9 (37.5%) in lower, and 12 (50.0%) in no expected efficacy class. DS composition showed 36 substances, 18 with no literature on male fertility and 18 showing positive effect on sperm parameters, thus considered potentially active ingredients (PAI). All DS were mixtures of ingredients, containing from 2 to 17 different substances. Fifteen supplements (65.2%) contained at least 1 ingredient without evidence of efficacy and 21 formulations had PAI dosed below mED. Some PAI were associated to the improvement of specific sperm parameters.

CONCLUSIONS

DS were usually blends of many substances that are frequently employed at negligible dose or without any evidence of efficacy on male reproduction. Some ingredients have been demonstrated to be effective on specific sperm parameters by RCTs. We report a list of ingredients with potential efficacy on specific sperm parameters, aimed to allow a tailored use of DS.

PATIENT SUMMARY

The market of DS for male infertility offers products with potential efficacy in the improvement of sperm parameters but also many with uncertain effects. Based on current scientific literature, our study can help in the choice of DS that are more likely to be effective on specific sperm alterations, so providing the best supplementation for each patient.

Seminal oxidation-reduction potential as a possible indicator of impaired sperm parameters in Turkish population

Oxidative stress (OS) has been shown to have a key role in male infertility. Recently, a new measurement method has been developed to measure the overall oxidation-reduction potential (ORP) in a semen sample known as the MiOXSYS system. The aim of this study was to investigate the correlation of sperm parameters with oxidative stress levels determined by ORP and to evaluate whether the current limit is able to distinguish abnormal sperm parameters from normal ones in Turkish population. Semen samples of 121 patients who applied for infertility investigation were divided into two groups as (OS +; n:39) and (OS -; n:82). Semen parameters were compared between groups. Sperm concentration, total motility and progressive motility were found to be significantly lower in OS (+) patients compared to those OS (-), while immotile sperm count was significantly higher in OS (+) patients. Oxidative stress determined by MiOXSYS system was found to be related to reduced sperm parameters in Turkish population, which may be used as an indicator of poor sperm parameters and a support to routine semen analysis. In addition, recommended reference value was found to be reliable in distinguishing normal from impaired semen parameters.

Antioxidant treatment of increased sperm DNA fragmentation: Complex combinations are not more successful

OBJECTIVE

Oral antioxidant supplementation is part of the treatment of infertility associated with oxidative stress-related sperm damage. It is possible to assume that the combined use of antioxidants will be better than single agent use. The purpose of this study was to compare the effectiveness of different antioxidant combinations in infertile men with increased sperm DNA fragmentation.

MATERIALS AND METHODS

We retrospectively reviewed the records of 637 patients who underwent antioxidant support therapy for increased sperm DNA damage between 2014 and 2019. Patients with DNA damage of 30% or more were included study.

RESULT

A total of 163 patients with follow-up data and who fulfilled the study criteria were included in the study. There were four different treatment groups. No statistically significant differences were found between the groups. After 3 months of antioxidant treatment, there was a statistically significant decrease in sperm DNA damage in all treatment groups. However, there was no statistically significant difference between the treatment groups.

CONCLUSIONS

The complexity of the antioxidant combination may not contribute to the success of the treatment or may cause possible side effects, increase the cost of treatment and decrease patient compliance.

Impact of oxidative stress on semen parameters in normozoospermic infertile men: a case–control study

Background

Oxidative stress has been implicated in male infertility through decrease in sperm quality. However, men with normal semen parameters (normozoospermia) may be unable to fertilize their partners even when they have normal sperm function. Thus, they would be considered infertile. The purpose of this study was to investigate the role of oxidative stress in the pathogenesis of unexplained male infertility.

Methods

In this case–control study, infertile men with normozoospermia (n = 46) and fertile control group (n = 21) underwent seminal fluid analyses according to WHO 2010 criteria. Serum and seminal plasma levels of total antioxidant capacity (TAC), glutathione, malondialdehyde, uric acid and albumin were also measured using colorimetric methods.

Results

The level of total antioxidant capacity in both serum and seminal plasma was significantly lower in normozoospermic infertile men in comparison with fertile group (p < 0.0001). However, no significant differences were observed in serum and seminal plasma levels of glutathione, uric acid, albumin and malondialdehyde between infertile and fertile groups.

Conclusion

Low TAC level induces oxidative stress and consequently causes sperm dysfunction and male infertility. Estimation of TAC can be a useful tool in the diagnosis of male infertility. Antioxidant supplementation should be considered in the treatment of oxidative stress-induced male infertility.

The ameliorative effects of Lactobacillus coagulans and Lactobacillus casei probiotics on CCl4-induced testicular toxicity based on biochemical, histological and molecular analyses in rat

Probiotics are commonly present in foods and role as dietary adjuncts and alternatives to pharmacological products in many medical fields. The aim of this study was to investigate the effects of Lactobacillus coagulans and Lactobacillus casei probiotics on carbon tetrachloride (CCl₄ )-induced reproductive injury and sperm toxicity in rats. Thirty-two Wistar rats were divided into four groups as follows: sham, CCl₄ (2 ml/kg), L. casei probiotic + 2 ml/kg CCl₄ and L. coagulans probiotic + 2 ml/kg CCl₄ . On the 36th day after the intervention, serum levels of follicle-stimulating hormone (FSH), luteinising hormone (LH) and total testosterone (T), as well as catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities, were measured. Testicular malondialdehyde (MDA) level, the expressions of apoptosis-related genes (Bcl-2 and Bax), Bax/Bcl-2 ratio, histomorphometric indices such as tubular differentiation index (TDI), repopulation index (RI), spermiogenesis index (SPI) and sperm parameters were evaluated. L. casei and L. coagulans probiotics improved the levels of reproductive hormones and antioxidant capacity in rats. Both the probiotics, especially L. casei, increased the rate spermatogenesis which accompanied with significant increments in testicular TDI, RI and SPI. Furthermore, both probiotics down-regulated Bax and up-regulated Bcl-2, following by decreased Bax/Bcl-2 ratio. Our key findings indicated that L. casei and L. coagulans have protective effects against CCl₄ -induced testicular toxicity.

Toxicity associated with long term use of aluminum cookware in mice: A systemic, genetic and reproductive perspective

Studies on the toxic effects of cooking with aluminum pots are limited and none of them have explored its impact on the genetic material in germ and somatic cells. Therefore, this study investigated the cytogenotoxic effect of boiled water from new, 3- and 6-year old aluminum pots in germ and somatic cells viz-a-vis mouse sperm morphology test and sperm count; and the bone marrow micronucleus test. The mice were allowed to freely drink the boiled water from the different aluminum pots for 3, 4, and 5 weeks. The heavy metal analysis showed that As, Pb, Cd, and Al were present in the boiled water samples at different concentrations with the 6-year old pot having the highest concentrations of Pb, Cd, and Al. There were duration of exposure and age of pot-dependent significant increase in abnormal sperm cells and a significant decrease total mean sperm count of exposed mice. Similarly, there was a statistically significant increase in micronucleated polychromatic erythrocytes and nuclear abnormalities in the exposed mice that increased dependently upon the age of the cookware. Finally there were significantly increased activities of serum AST and ALT; and the liver concentrations of MDA, SOD and CAT in boiled water exposed mice. The findings of this study revealed that boiled water from aluminum pots is capable of inducing cytotoxic and genotoxic effects, especially as the pot ages.

Does in vitro application of pentoxifylline have beneficial effects in assisted male reproduction?

Application of nonspecific phosphodiesterases inhibitors, such as pentoxifylline (PTX), is a strategy utilised to aid sperm selection from immotile sperm samples prior to ICSI. No extensive studies have yet been performed to verify the safety of the clinical outcomes of ICSI after PTX administration. In this article, we summarise the data reported in the literature that assess the implication of in vitro usage of PTX on sperm parameters, as well as clinical outcomes during assisted male reproduction programme.

Decreased prostate-specific membrane antigen levels in the seminal plasma of oligoasthenoteratozoospermic men

Prostate-specific membrane antigen (PSMA) is a transmembrane glycoprotein with glutamate carboxypeptidase activity. However, its precise function in the prostate, prostasomes and seminal plasma with regard to male fertility remains unknown. This study was conducted to investigate the seminal plasma PSMA levels in fertile men and patients with oligoasthenoteratozoospermia (OAT) and to analyse its association with sperm parameters. Twenty fertile men and twenty patients admitted at the urology clinic of our institution with the diagnosis of OAT were included in the study. Following semen analysis, seminal plasma was isolated from semen ejaculates. PSMA concentrations in the seminal plasma were determined by ELISA. The correlations between seminal PSMA concentrations and semen parameters were statistically analysed. Seminal plasma PSMA concentration was significantly lower in OAT patients compared to fertile controls (p < .01). In fertile men, PSMA concentration was significantly correlated with the sperm concentration (r = -.481, p < .05), whereas in the patient group no statistically significant correlation was found between the sperm parameters and seminal PSMA level. This is the first study in the literature to investigate PSMA levels in the seminal plasma from infertile men. Decreased levels of seminal plasma PSMA might suggest a role for compromised prostasome function in the pathogenesis of OAT syndrome.

Simple and reliable determination of Zn and some additional elements in seminal plasma samples by using total reflection X-ray fluorescence spectroscopy

Trace elements are essential for the normal spermatogenesis of mammals and play a critical role in sperm quality and pathological processes e.g. inflammation. Consequently, multi-elemental analysis of seminal plasma (SP) may provide significant information on physiological and pathophysiological processes occurring in the male reproductive tract. Therefore, the development of a simple, fast and reliable method for seminal plasma (SP) analysis by total reflection X-ray fluorescence spectrometry (TXRF) could be useful for both, scientific and clinical studies. In this study, a detailed assessment of the sample preparation parameters and measurement conditions, including analysis of the shape and element distribution of the deposited residue on the reflector by micro X-ray fluorescence spectrometry, was carried out. Using the best analytical conditions, limits of detection for trace elements were found to be in the range of 0.04-0.3 mg kg-1. Trueness and precision of the results, evaluated by spiked SP sample analysis, were in most cases acceptable with recovery values in the range of 87-109% and relative standard deviations 3-12% (n = 5). The developed TXRF method was applied for the analysis of several SP samples from patients with different diagnoses and the results were compared with those obtained by ICP-OES. Among the studied trace elements with a role in the antioxidant defence system only Zn could be quantified and some differences in Zn concentrations among studied groups were observed. However, further studies on a large number of samples are required to define the exact relationship between the element composition and semen quality.

Supplementing post-wash asthenozoospermic human spermatozoa with coenzyme Q10 for 1 hr in vitro improves sperm motility, but not oxidative stress

We investigated the effect of supplementing post-wash asthenozoospermic spermatozoa with coenzyme Q10 (CoQ10) in vitro, which may reduce oxidative stress and improve sperm motility. Semen samples were collected from 39 men with asthenozoospermia, and their spermatozoa were isolated by two-layer Percoll density-gradient centrifugation. Kinetic parameters of the isolated spermatozoa (baseline before intervention) were determined immediately by computer-aided semen analysis. Total anti-oxidant capacity and protein carbonyl levels, as markers of oxidative stress, were also measured in the baseline spermatozoa. The baseline spermatozoa suspension was divided equally into two portions, one for CoQ10 supplementation (50 µg/ml for 1 hr) and the other as an un-supplemented vehicle control. The total motility of the CoQ10-supplemented spermatozoa was significantly higher than in the control (p = .009) and progressive motility tended to be higher (p = .053). Immotile sperm concentration in the CoQ10-supplemented spermatozoa was significantly lower than in both the baseline (p = .026) and control (p = .009). Total anti-oxidant capacity and protein carbonyl levels between the baseline, CoQ10-supplemented and control spermatozoa were not significantly different. Our data suggest that CoQ10 treatment reactivated sperm motility. We propose short-term supplementation of post-wash asthenozoospermic spermatozoa with CoQ10 before intrauterine insemination.

Does salinity variation increase synergistic effects of triclosan and carbon nanotubes on Mytilus galloprovincialis? Responses on adult tissues and sperms

The use of carbon nanotubes (CNTs) is rapidly increasing and several scientific studies have addressed their toxicological properties. However, only a very small number of publications have deal with the interaction between CNTs and other molecules. Triclosan (TCS) is an antibacterial agent used in personal care and household products. Commonly detected in aquatic ecosystems, there is a strong evidence that aquatic biota is sensitive to this compound. Aside from emergent pollutants, aquatic organisms are continuously subjected to abiotic variations including salinities. Therefore, the main goal of the present study was to better understand how physio-chemical interactions of CNTs with TCS under different salinity levels (37, 28 and 19) affect the mussel species Mytilus galloprovincialis through the evaluation of biochemical alterations on gametes (sperms) and adult tissues, providing more ecologically relevant information on organisms' responses. The results showed toxicological effects in terms of sperm metabolic activity and intracellular reactive oxygen species production as well as cellular damage and alteration of metabolic capacity at the adult's stage when exposed to both contaminants acting alone and in combination, under tested salinities. Moreover, when the mussels were exposed to the combination of both contaminants, they showed major toxic impacts on both assessed biological levels (adult tissues and sperms) especially under control salinity. This suggests that toxicity upon mixture exposure compared to single-substance exposure may impair mussels' populations, affecting reproduction success and growth.

Oxidative Stress is Associated with Reduced Sperm Motility in Normal Semen

Infertility is among the most serious medical problems worldwide. Male factors contribute to 40%-50% of all infertility cases, and approximately 7% of men worldwide are affected by infertility. Spermatozoa are extremely vulnerable to oxidative insult. Oxidative stress results in axonemal damage and increased midpiece sperm morphological defects, which lead to reduced sperm motility. The aim of the study is to evaluate the association between sperm motility and the levels of selected antioxidants, cytokines, and markers of oxidative damage in the seminal plasma.The study group included 107 healthy males, who were split into two subgroups based on the percentage of motile spermatozoa after 1 hr: low motility (LM, n = 51) and high motility (HM, n = 56).The glucose-6-phosphate dehydrogenase (G6PD) activity was 52% lower in the LM group compared to that in the HM group. The level of malondialdehyde (MDA) was 12% higher in the LM group compared to that in the HM group. Similarly, the median values of interleukin (IL)-1β, IL-10, IL-12, and tumor necrosis factor alpha (TNF-α) were higher in the LM group than those in the HM group. Results of the present study revealed that the percentage of motile spermatozoa after 1 hr correlated positively with the levels of IL-1β, IL-10, IL-12, and TNFα.The lower motility of spermatozoa in healthy men is associated with a decreased activity of G6PD and increased levels of cytokines, which may be related to increased oxidative stress in seminal plasma that manifests as an increased level of MDA.

GPx8 Expression in Rat Oocytes, Embryos, and Female Genital Organs During Preimplantation Period of Pregnancy

This study aimed to detect the presence of glutathione peroxidase 8 (GPx8) in rat during preimplantation period of pregnancy. Females were killed on first (D1), third (D3), and fifth (D5) day of pregnancy. The presence of GPx8 in embryos was detected under the confocal microscope, the presence of GPx8 in genital organs was confirmed immunohistochemically, and the amount of GPx8 was determined using densitometry. We found that GPx8 is dispersed in the cytoplasm of oocytes, while after fertilization, it is concentrated in granules. From 4-cell stage till blastocyst, GPx8 reaction was found in the perinuclear region. In the ovary, GPx8 was seen in granulosa-lutein cells, in plasma of blood vessels, and inside Graafian follicles. In oviduct, GPx8 was detected in the plasma and in the extracellular matrix (ECM). Moreover, epithelial cells of isthmus were positive. In uterus, GPx8 was observed in the uterine glands, in the plasma, and in ECM. On D5, the enzyme disappeared from the uterine glands and appeared in fibroblasts. Densitometry revealed that the highest amount of GPx8 was on D1 and subsequently declined. To our knowledge, this is the first paper describing GPx8 presence in the oocytes, preimplantation embryos, and female genital organs in mammals. Our results improve the understanding of antioxidant enzymes presence during pregnancy in defense against oxidative stress, which is considered to be one of the main causes of infertility.

"Emerging role of Novel Seminal Plasma Bio-markers in Male Infertility: A Review"

Male infertility has emerged as an important cause of infertility worldwide. There are many factors affecting male fertility and research is going on to know impact of various factors on sperm functions. Semen analysis is gold standard diagnostic test for male infertility, but it is crude method for estimation of male infertility as seminal composition gets affected by environmental factors, infections, other pathologies, hence, results of semen analysis either becomes normal/ambiguous, leading to failure of diagnosis and delayed treatment. Hence, with need of newer, better tests for assessing male factor infertility, seminal plasma is being tested for biomarkers. Seminal plasma is considered gold mine for male fertility as it contains molecules from male reproductive glands which play important role in sperm function. Study of seminal plasma molecules can give an idea about sperm concentration, motility, morphology and cause of infertility and can serve as biomarkers for male infertility. Present review briefs on some of these novel seminal plasma biomarkers which may play significant role in male fertility and can be used in future for better identification, assessment of infertile males.

METHODOLOGY

Literature from 1985 to 2019 was searched from various databases including PUBMED, SCOPUS, Google Scholar on seminal plasma biomarkers using keywords: "seminal plasma protein biomarkers", "novel seminal plasma markers and male infertility", "hormones in seminal plasma and male infertility", "oxidative stress and male infertility", "Reactive Oxygen Species and sperm DNA", "immunoinfertility".

INCLUSION CRITERIA

All full length original or review articles or abstracts on seminal plasma markers and male infertility published in English language in various peer-reviewed journals were considered.

EXCLUSION CRITERIA

Articles published in languages other than English were excluded from the study.

RESULTS

Seminal plasma is a big reservoir of molecules derived from the various male reproductive glands which can be used as potential biomarkers of male fertility.

CONCLUSION

Hence, seminal plasma biomarkers can be used in future for better assessment of male factor infertility, its causes and may play an important role in management of male factor infertility.

Scientific landscape of oxidative stress in male reproductive research: A scientometric study

Unraveling the role of reactive oxygen species and associated oxidative stress (OS) in male reproduction is one of the key areas of male reproductive research. This article illustrates the scientific landscape of OS in male reproductive research over the past several decades (1941-2018) using a scientometric approach. Scientometric data (articles per year, authors, affiliations, journals, and countries) on OS related to male reproduction were retrieved from the Scopus database and analyzed for each decade. Our analysis revealed an increasing trend in OS-based male reproductive research from 1941 to 2018 with a steep raise in publications and research collaborations starting from the period 1991-2000 (R² = 0.81). Semen abnormalities and varicocele were the major areas investigated in relation to OS with the highest positive trend in publications from the time interval 1981-1990 to 2011-2018. Analysis of publications based on OS assessment techniques revealed chemiluminescence (n = 180) and evaluation of antioxidants (n = 300) as the most widely used direct and indirect tests, respectively. Furthermore, prognostic/diagnostic studies on OS evaluation increased significantly over the time. Our analysis highlights the evolution of OS in male reproductive research and its emergence as an important prognostic and diagnostic tool in the evaluation of male infertility.

The role of infections and leukocytes in male infertility

Declining birth rates are one of the problems facing society today. Male counterparts are responsible for about half of the infertility cases, and genitourinary tract infections may play a contributing role in approximately 15% of male infertility cases. Leukocytospermia is an established indicator of infection in the male urogenital tract, although other microorganisms such as bacteria and virus may also be contributors to the etiology of male infertility. The pathophysiology of these infectious agents may be initiated by a local inflammatory reaction resulting in an increase in reactive oxygen species (ROS). This results in testicular injury, thereby affecting sperm morphology, sperm motility, sperm viability and elevation of the seminal leukocyte as a result of the genital tract infection. The infectious and inflammatory changes can result in male infertility. It is proposed that high concentrations of seminal leukocyte and infectious agents may affect sperm function resulting in clumping of motile spermatozoa, decreasing acrosomal functionality and also causing alterations in sperm morphology. However, the literature has poorly clarified the role of infection in male infertility, provoking further debate and research on this topic.

ProAKAP4 as Novel Molecular Marker of Sperm Quality in Ram: An Integrative Study in Fresh, Cooled and Cryopreserved Sperm

To improve artificial insemination protocols in ovine species it is crucial to optimize sperm quality evaluation after preservation technologies. Emerging technologies based on novel biomolecules and related to redox balance and proteins involved in sperm motility such as ProAKAP4 could be successfully applied in ram sperm evaluation. In this work, a multiparametric analysis of fresh, cooled, and cryopreserved ram sperm was performed at different complexity levels. Samples were evaluated in terms of motility (total motility, progressive motility, and curvilinear velocity), viability, apoptosis, content of reactive oxygen species, oxidation‒reduction potential, and ProAKAP4 expression and concentration. As expected, cryopreserved samples showed a significant decrease of sperm quality (p < 0.05), evidencing different freezability classes among samples that were detected by ProAKAP4 analyses. However, in cooled sperm no differences were found concerning motility, viability, apoptosis, ROS content, and redox balance compared to fresh sperm that could explain the reported decrease in fertility rates. However, although the proportion of sperm ProAKAP4 positive-cells remained unaltered in cooled sperm compared to fresh control, the concentration of this protein significantly decreased (p < 0.05) in cooled samples. This altered protein level could contribute to the decrease in fertility rates of cooled samples detected by some authors. More importantly, ProAKAP4 can be established as a promising diagnostic parameter of sperm quality allowing us to optimize sperm conservation protocols and finally improve artificial insemination in ovine species.

Metformin Ameliorates Testicular Function and Spermatogenesis in Male Mice with High-Fat and High-Cholesterol Diet-Induced Obesity

The aim of this study was to investigate the effects of metformin supplementation on metabolic dysfunction, testicular antioxidant capacity, apoptosis, inflammation and spermatogenesis in male mice with high-fat and high-cholesterol diet-induced obesity. Forty male C57BL/6 mice were fed a normal diet (NC group, n = 10) or a high-fat and high-cholesterol diet (HFC group, n = 30) for 24 weeks, and mice randomly chosen from the HFC group were later treated with metformin for the final 8 weeks of HFC feeding (HFC + Met group, n = 15). Compared with the HFC group, the obese mice supplemented with metformin exhibited improved blood cholesterol, glucose and insulin resistance. The HFC group diminishes in the sperm motility and normal sperm morphology, while the poorer maturity of testicular spermatogenesis was improved by metformin treatment. The HFC group exhibited a higher estradiol level and a lower 17β-HSD protein expression. Further analyses showed that metformin treatment increased the activities of superoxide dismutase, catalase and glutathione peroxidase and reduced lipid peroxidation. Nevertheless, both the HFC and HFC + Met groups exhibited increased expressions of apoptosis and inflammation proteins in the testis. Metformin treatment ameliorated obesity-induced poor testicular spermatogenesis and semen quality through increasing the testosterone level and antioxidant capacity.

Discovery of the Involvement in DNA Oxidative Damage of Human Sperm Nuclear Basic Proteins of Healthy Young Men Living in Polluted Areas

DNA oxidative damage is one of the main concerns being implicated in severe cell alterations, promoting different types of human disorders and diseases. For their characteristics, male gametes are the most sensitive cells to the accumulation of damaged DNA. We have recently reported the relevance of arginine residues in the Cu(II)-induced DNA breakage of sperm H1 histones. In this work, we have extended our previous findings investigating the involvement of human sperm nuclear basic proteins on DNA oxidative damage in healthy males presenting copper and chromium excess in their semen. We found in 84% of those males an altered protamines/histones ratio and a different DNA binding mode even for those presenting a canonical protamines/histones ratio. Furthermore, all the sperm nuclear basic proteins from these samples that resulted were involved in DNA oxidative damage, supporting the idea that these proteins could promote the Fenton reaction in DNA proximity by increasing the availability of these metals near the binding surface of DNA. In conclusion, our study reveals a new and unexpected behavior of human sperm nuclear basic proteins in oxidative DNA damage, providing new insights for understanding the mechanisms related to processes in which oxidative DNA damage is implicated.

In Vitro Effects of Titanium Dioxide Nanoparticles (TiO2NPs) on Cadmium Chloride (CdCl2) Genotoxicity in Human Sperm Cells

The environmental release of titanium dioxide nanoparticles (TiO₂NPs) associated with their intensive use has been reported to have a genotoxic effect on male fertility. TiO₂NP is able to bind and transport environmental pollutants, such as cadmium (Cd), modifying their availability and/or toxicity. The aim of this work is to assess the in vitro effect of TiO₂NPs and cadmium interaction in human sperm cells. Semen parameters, apoptotic cells, sperm DNA fragmentation, genomic stability and oxidative stress were investigated after sperm incubation in cadmium alone and in combination with TiO₂NPs at different times (15, 30, 45 and 90 min). Our results showed that cadmium reduced sperm DNA integrity, and increased sperm DNA fragmentation and oxidative stress. The genotoxicity induced by TiO₂NPs-cadmium co-exposure was lower compared to single cadmium exposure, suggesting an interaction of the substances to modulate their reactivity. The Quantitative Structure-Activity Relationship (QSAR) computational method showed that the interaction between TiO₂NPs and cadmium leads to the formation of a sandwich-like structure, with cadmium in the middle, which results in the inhibition of its genotoxicity by TiO₂NPs in human sperm cells.

Seminal Plasma Proteome as an Indicator of Sperm Dysfunction and Low Sperm Motility in Chickens

Molecular mechanisms underlying sperm motility have not been fully explained, particularly in chickens. The objective was to identify seminal plasma proteins associated with chicken sperm motility by comparing the seminal plasma proteomic profile of roosters with low sperm motility (LSM, n = 4) and high sperm motility (HSM, n = 4). Using a label-free MS-based method, a total of 522 seminal plasma proteins were identified, including 386 (∼74%) previously reported and 136 novel ones. A total of 70 differentially abundant proteins were defined, including 48 more-abundant, 15 less-abundant, and seven proteins unique to the LSM group (specific proteins). Key secretory proteins like less-abundant adhesion G-protein coupled receptor G2 (ADGRG2) and more-abundant serine peptidase inhibitor Kazal-type 2 (SPINK2) in the LSM suggested that the corresponding secretory tissues played a crucial role in maintaining sperm motility. Majority (80%) of the more-abundant and five specific proteins were annotated to the cytoplasmic domain which might be a result of higher plasma membrane damage and acrosome dysfunction in LSM. Additionally, more-abundant mitochondrial proteins were detected in LSM seminal plasma associated with lower spermatozoa mitochondrial membrane potential (ΔΨm) and ATP concentrations. Further studies showed that the spermatozoa might be suffering from oxidative stress, as the amount of spermatozoa reactive oxygen species (ROS) were largely enhanced, seminal malondialdehyde (MDA) concentrations were increased, and the seminal plasma total antioxidant capacity (T-AOC) were decreased. Our study provides an additional catalogue of chicken seminal plasma proteome and supports the idea that seminal plasma could be as an indicator of spermatozoa physiology. More-abundant of acrosome, mitochondria and sperm cytoskeleton proteins in the seminal plasma could be a marker of sperm dysfunction and loss of motility. The degeneration of spermatozoa caused by the reduced seminal T-AOC and enhanced oxidative stress might be potential determinants of low sperm motility. These results could extend our understanding of sperm motility and sperm physiology regulation.

Positive effect of nutraceuticals on sperm DNA damage in selected infertile patients with idiopathic high sperm DNA fragmentation

BACKGROUND

The use of nutraceuticals to improve sperm parameters and male fertility is debatable, even if evidence suggests that selected infertile patients might benefit from their use. In particular, oxidative stress might play a role in idiopathic male infertility, leading to sperm membrane damage and high sperm DNA fragmentation (SDF). The aim of this study was to evaluate, in selected idiopathic infertile men with high SDF, the effect on sperm DNA damage and on standard semen parameters of a nutraceutical formulation containing myoinositol, alpha lipoic acid, coenzyme Q10, selenium, zinc and B vitamins.

METHODS

The study included 60 idiopathic infertile men with DNA fragmentation index (DFI) >20%. Semen analysis and DFI determination were assessed at baseline and after three months of nutraceutical treatment. Primary outcome was change in DFI.

RESULTS

Semen volume, sperm concentration, total sperm count, sperm motility and sperm morphology did not change after treatment. Instead, sperm vitality significantly increased (65.9±11.8% pre-treatment vs. 69.4±9.4% post-treatment, P<0.05) and DFI significantly decreased (33.5±10.1% pre-treatment vs. 26.8±8.7% post-treatment, P=0.0001) after treatment. The percentage of men with normal standard sperm parameters significantly increased (15% vs. 30%, P<0.05). The mean decrease in DFI was -6.7±1.4% and the percentage of men with DFI ≤30% after treatment was 75.0% compared to 48.3% pre-treatment (P<0.005). Higher pre-treatment DFI (and no other parameters) correlated with greater DFI reduction after treatment.

CONCLUSIONS

Nutraceuticals might be effective in idiopathic infertile men with high DFI to reduce SDF, increase sperm vitality and globally improve semen parameters.

Protective effects of vitamin E on aluminium sulphate-induced testicular damage

Male infertility can be caused by environmental factors, genetic defects, physiological and endocrine deficiencies and testicular pathologies. Aluminium (Al) can cause male infertility through a number of mechanisms. The aim of our study was thus to determine whether vitamin E (VitE) has protective effects on Al-induced testicular damage, which was determined according to sperm counts and morphology and using the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) method. Thirty-four male Wistar rats (250-300 g) were randomly assigned to control (no procedures performed; n = 6) or 0.2 mL intraperitoneal injection group (n = 7 each; three times per week for 4 weeks): sham (distilled water), 10 mg/kg Al, 500 mg/kg VitE and 10 mg/kg Al plus 500 mg/kg VitE (Al + VitE). Sperm samples were evaluated for andrological parameters. The testes were examined by haematoxylin/eosin. The epithelial thickness and areas were calculated and Johnsen scores were determined for the germinal epithelium; the apoptotic indices were determined from TUNEL staining. For Al, the bonds between the germinal epithelial cells were broken in some tubules, and there were unidentified cells in the lumen of some tubules. For control, sham and VitE, normal morphology of the germinal epithelium was generally preserved. With Al + VitE, the full germinal epithelium cell series was maintained, with only mature sperm in the lumen. TUNEL-positive cells were significantly higher with Al compared to control and sham (p < 0.05). For Al + VitE, the number of apoptotic cells was reduced compared to Al alone and was therefore similar to control, sham and VitE (p > 0.05). Our findings show that Al caused testicular damage. VitE reduced the number of apoptotic cells during the damage caused by Al.

Progress in Research on Sperm DNA Fragmentation

With the increasing incidence of male infertility, routine detection of semen is insufficient to accurately assess male fertility. Infertile men, who have lower odds of conceiving naturally, exhibit high levels of sperm DNA fragmentation (SDF). The mechanisms driving SDF include abnormal spermatogenesis, oxidative stress damage, and abnormal sperm apoptosis. As these factors can induce SDF and subsequent radical changes leading to male infertility, detection of the extent of SDF has become an efficient routine method for semen analysis. Although it is still debated, SDF detection has become a research hotspot in the field of reproductive medicine as a more accurate indicator for assessing sperm quality and male fertility. SDF may be involved in male infertility, reproductive assisted outcomes, and growth and development of offspring. The effective detection methods of SDF are sperm chromatin structure analysis (SCSA), terminal transferase-mediated dUTP end labeling (TUNEL) assay, single-cell gel electrophoresis (SCGE) assay, and sperm chromatin dispersion (SCD) test, and all of these methods are valuable for assisted reproductive techniques. Currently, the preferred method for detecting sperm DNA integrity is SCSA. However, the regulation network of SDF is very complex because the sperm DNA differs from the somatic cell DNA with its unique structure. A multitude of molecular factors, including coding genes, non-coding genes, or methylated DNA, participate in the complex physiological regulation activities associated with SDF. Studying SDF occurrence and the underlying mechanisms may effectively improve its clinical treatments. This review aimed to outline the research status of SDF mechanism and detection technology-related issues, as well as the effect of increased SDF rate, aiming to provide a basis for clinical male infertility diagnosis and treatment.

Microbiota and Human Reproduction: The Case of Male Infertility

The increasing interest in metagenomics is enhancing our knowledge regarding the composition and role of the microbiota in human physiology and pathology. Indeed, microbes have been reported to play a role in several diseases, including infertility. In particular, the male seminal microbiota has been suggested as an important factor able to influence couple’s health and pregnancy outcomes, as well as offspring health. Nevertheless, few studies have been carried out to date to deeper investigate semen microbiome origins and functions, and its correlations with the partner’s reproductive tract microbiome. Here, we report the state of the art regarding the male reproductive system microbiome and its alterations in infertility.

Coenzyme Q10 Improves Sperm Parameters, Oxidative Stress Markers and Sperm DNA Fragmentation in Infertile Patients with Idiopathic Oligoasthenozoospermia

Purpose

Oxidative stress and sperm DNA fragmentation (SDF) are potential contributing factors for idiopathic male infertility. Coenzyme Q10 (CoQ10) have been reported to be effective in the treatment of idiopathic male infertility, in general, owing to its antioxidant properties. Thus, the present study intends to investigate the effects of CoQ10 therapy on semen parameters, oxidative stress markers and SDF in infertile men, specifically with idiopathic oligoasthenozoospermia (OA).

Materials and Methods

In this case-control study, sixty-five infertile patients with idiopathic OA and forty fertile men (control) were included. All participants underwent semen analysis based on the World Health Organization guidelines (5th edition, 2010). Patients received CoQ10 at the dose of 200 mg/d orally for three months. Seminal plasma CoQ10, total antioxidant capacity (TAC), total reactive oxygen species (ROS), glutathione peroxidase (GPx), and SDF levels were measured in controls (baseline) and infertile patients pre- and post-CoQ10 treatment.

Results

CoQ10 treatment for three months significantly improved sperm concentration (p<0.05), progressive motility (p<0.05), total motility (p<0.01), seminal fluid CoQ10 concentration (p<0.001), TAC (p<0.001), and GPx (p<0.001) levels in infertile men with OA. Further, ROS level (p<0.05) and SDF percentage (p<0.001) were reduced in OA patients as compared to the baseline. CoQ10 levels also correlated positively with sperm concentration (r=0.48, p=0.01) and total motility (r=0.59, p=0.003) while a negative correlation was recorded between SDF and sperm motility (r=−0.54, p=0.006).

Conclusions

CoQ10 supplementation for three months could improve semen parameters, oxidative stress markers and reduce SDF in infertile men with idiopathic OA.

Ghrelin alleviates endoplasmic reticulum stress and inflammation-mediated reproductive dysfunction induced by stress

PURPOSE

Psychological stress exists widely in modern society and results in the disruption of testicular tight junctions, germ cell apoptosis, and the disorder of fertility hormones and even causes infertility. Ghrelin (GHRL), a 28-amino acid peptide secreted mainly by the stomach and pancreas, has been reported to alleviate male reproductive injury through inhibiting apoptosis. However, whether GHRL has a beneficial effect on psychological stress-induced testicular injury and the possible mechanisms remain poorly understood.

METHODS

Male mice were immobilized in Decapicone bags for 3 h daily for 14 days treated with or without GHRL (i.p. 100 mg/kg body weight). Body weight and testicular weight were measured. Histological alterations and apoptosis were examined by H.E. staining and TUNEL staining, respectively. The expression of endoplasmic reticulum (ER) stress markers, inflammatory cytokines, Toll-like receptor 4 (TLR4), and nuclear factor-κB (NF-κB) in the testes was investigated.

RESULTS

Exposure to stress caused testicular histological alterations, an elevation of the Johnsen score, and germ cell apoptosis, while GHRL partially alleviated the adverse effects. The expression of ER stress marker proteins, including GRP78, CHOP, ATF6, p-JNK, and XBP-1, was upregulated in the stress group; however, GHRL treatment significantly suppressed the activation of ER stress in the testes. GHRL also inhibited the expression of TNF-α, IL-1β, IL-6, IL-10, TLR4, and NF-κB.

CONCLUSIONS

GHRL alleviated testicular injury induced by ER stress and inflammation which is associated with the TLR4/NF-κB signaling pathway, and these findings may provide a novel strategy for preventing and treating reproductive dysfunction.

The effect of vitamin E & vitamin B on sperm function in rat varicocele model

We assessed the effect of vitamin E and vitamin B (Vit E & Vit B) and their combination on sperm functional parameters in the rat varicocele model. Male rats (n = 120) were divided into control (n = 30), sham (n = 30) and varicocele induction (n = 60) groups. After 2 months, 10 rats from each group were sacrificed to verify varicocele model. This part of results showed that sperm parameters, DNA damage, lipid peroxidation and residual histone were adversely effected in the varicocele group. From the 50 remaining rats in varicocele group, 10 rats received Vit B complex (6, 9.6, 30.4, 9.6 and 0.006 mg/kg for B6, B2, B9, B1 and B12 respectively), 10 rats received Vit E (40 mg/kg), 10 rats received Vit B & E, 10 rats only received water and 10 rats were only received sesame oil as a solvent for Vit E, for 2 months. From 40 remaining rats in control and sham groups, 20 rats only received water and other 20 rats only received sesame oil for 2 months. Then, all the aforementioned parameters were assessed. These results showed that Vit B antioxidant was more efficient in improvement of sperm parameters, chromatin integrity and lipid peroxidation in varicocelized rats compared with Vit E.

Sulforaphane Protects the Male Reproductive System of Mice from Obesity-Induced Damage: Involvement of Oxidative Stress and Autophagy

(1) Background: In recent decades, the prevalence of obesity has grown rapidly worldwide, thus causing many diseases, including male hypogonadism. Sulforaphane (SFN), an isothiocyanate compound, has been reported to protect the reproductive system. This research investigated the protective effect of SFN against obesity-induced impairment in the male reproductive system and explored the potential mechanism involved in mice. (2) Methods: One hundred thirty mice were divided into 5 groups (Control, DIO (diet-induced obesity), DIO + SFN 5 mg/kg, DIO + SFN 10 mg/kg, and DIO + SFN 20 mg/kg). The effects of SFN on the male reproductive system were determined based on the sperm count and motility, relative testes and epididymis weights, hormone levels, and pathological analyses. Oxidative stress was determined by measuring malondialdehyde (MDA), total antioxidant capacity (T-AOC), superoxide dismutase (SOD), glutathione (GSH), H₂O₂, catalase (CAT), and glutathione peroxidase (GSH-PX) levels. Protein expression of nuclear factor erythroid-2 related factor 2 (Nrf2), Kelch-like ECH-associated protein-1 (Keap1), Microtubule-associated protein light chain 3 (LC3), Beclin1, and P62 were determined by western blotting. (3) Results: High-fat diet (HFD)-induced obesity significantly decreased relative testes and epididymis weights, sperm count and motility, and testosterone levels but increased leptin and estradiol levels. SFN supplementation ameliorated these effects. Additionally, SFN administration inhibited the obesity-induced MDA accumulation and increased the SOD level. Western blot indicated that SFN had an important role in the downregulation of Keap1. Moreover, SFN treatment attenuated obesity-induced autophagy, as detected by LC3 and Beclin1. (4) Conclusions: SFN ameliorated the reproductive toxicity associated with obesity by inhibiting oxidative stress mediated by the nuclear factor erythroid-2 related factor 2/ antioxidant response element (Nrf2/ARE) signaling pathway and recovery of normal autophagy.