Leukocytes and oxidative stress: dilemma for sperm function and male fertility

The impact of mitochondrial impairments on sperm function and male fertility: a systematic review

BACKGROUND

Besides adenine triphosphate (ATP) production for sustaining motility, the mitochondria of sperm also host other critical cellular functions during germ cell development and fertilization including calcium homeostasis, generation of reactive oxygen species (ROS), apoptosis, and in some cases steroid hormone biosynthesis. Normal mitochondrial membrane potential with optimal mitochondrial performance is essential for sperm motility, capacitation, acrosome reaction, and DNA integrity.

RESULTS

Defects in the sperm mitochondrial function can severely harm the fertility potential of males. The role of sperm mitochondria in fertilization and its final fate after fertilization is still controversial. Here, we review the current knowledge on human sperm mitochondria characteristics and their physiological and pathological conditions, paying special attention to improvements in assistant reproductive technology and available treatments to ameliorate male infertility.

CONCLUSION

Although mitochondrial variants associated with male infertility have potential clinical use, research is limited. Further understanding is needed to determine how these characteristics lead to adverse pregnancy outcomes and affect male fertility potential.

Exogenous Oxidative Stress in Human Spermatozoa Induces Opening of the Mitochondrial Permeability Transition Pore: Effect on Mitochondrial Function, Sperm Motility and Induction of Cell Death

Oxidative stress (OS) and disrupted antioxidant defense mechanisms play a pivotal role in the etiology of male infertility. The alterations in reactive oxygen species (ROS) production and calcium (Ca2+) homeostasis are the main activators for the mitochondrial permeability transition pore (mPTP) opening. The mPTP opening is one of the main mechanisms involved in mitochondrial dysfunction in spermatozoa. This alteration in mitochondrial function adversely affects energy supply, sperm motility, and fertilizing capacity and contributes to the development of male infertility. In human spermatozoa, the mPTP opening has been associated with ionomycin-induced endogenous oxidative stress and peroxynitrite-induced nitrosative stress; however, the effect of exogenous oxidative stress on mPTP opening in sperm has not been evaluated. The aim of this study was to determine the effect of exogenous oxidative stress induced by hydrogen peroxide (H2O2) on mPTP opening, mitochondrial function, motility, and cell death markers in human spermatozoa. Human spermatozoa were incubated with 3 mmol/L of H2O2 for 60 min, and intracellular Ca2+ concentration, mPTP opening, mitochondrial membrane potential (ΔΨm), ATP levels, mitochondrial reactive oxygen species (mROS) production, phosphatidylserine (PS) externalization, DNA fragmentation, viability, and sperm motility were evaluated. H2O2-induced exogenous oxidative stress caused increased intracellular Ca2+, leading to subsequent mPTP opening and alteration of mitochondrial function, characterized by ΔΨm dissipation, decreased ATP levels, increased mROS production, and the subsequent alteration of sperm motility. Furthermore, H2O2-induced opening of mPTP was associated with the expression of apoptotic cell death markers including PS externalization and DNA fragmentation. These results highlight the role of exogenous oxidative stress in causing mitochondrial dysfunction, deterioration of sperm motility, and an increase in apoptotic cell death markers, including PS externalization and DNA fragmentation, through the mPTP opening. This study yielded new knowledge regarding the effects of this type of stress on mitochondrial function and specifically on mPTP opening, factors that can contribute to the development of male infertility, considering that the role of mPTP in mitochondrial dysfunction in human sperm is not completely elucidated. Therefore, these findings are relevant to understanding male infertility and may provide an in vitro model for further research aimed at improving human sperm quality.

Leukocytospermia and/or Bacteriospermia: Impact on Male Infertility

Infertility is a globally underestimated public health concern affecting almost 190 million people, i.e., about 17.5% of people during their lifetime, while the prevalence of male factor infertility is about 7%. Among numerous other causes, the prevalence of male genital tract infections reportedly ranges between 10% and 35%. Leukocytospermia is found in 30% of infertile men and up to 20% in fertile men. Bacterial infections cause an inflammatory response attracting leukocytes, which produce reactive oxygen species (ROS) and release cytokines, both of which can cause damage to sperm, rendering them dysfunctional. Although leukocytospermia and bacteriospermia are both clinical conditions that can negatively affect male fertility, there is still debate about their impact on assisted reproduction outcomes and management. According to World Health Organization (WHO) guidelines, leukocytes should be determined by means of the Endtz test or with monoclonal antibodies against CD15, CD68 or CD22. The cut-off value proposed by the WHO is 1 × 106 peroxidase-positive cells/mL. For bacteria, Gram staining and semen culture are regarded as the "gold standard", while modern techniques such as PCR and next-generation sequencing (NGS) are allowing clinicians to detect a wider range of pathogens. Whereas the WHO manual does not specify a specific value as a cut-off for bacterial contamination, several studies consider semen samples with more than 103 colony-forming units (cfu)/mL as bacteriospermic. The pathogenic mechanisms leading to sperm dysfunction include direct interaction of bacteria with the male germ cells, bacterial release of spermatotoxic substances, induction of pro-inflammatory cytokines and ROS, all of which lead to oxidative stress. Clinically, bacterial infections, including "silent" infections, are treatable, with antibiotics being the treatment of choice. Yet, non-steroidal antiphlogistics or antioxidants should also be considered to alleviate inflammatory lesions and improve semen quality. In an assisted reproduction set up, sperm separation techniques significantly reduce the bacterial load in the semen. Nonetheless, contamination of the semen sample with skin commensals should be prevented by applying relevant hygiene techniques. In patients where leukocytospermia is detected, the causes (e.g. infection, inflammation, varicocele, smoking, etc.) of the leukocyte infiltration have to be identified and addressed with antibiotics, anti-inflammatories or antioxidants in cases where high oxidative stress levels are detected. However, no specific strategy is available for the management of leukocytospermia. Therefore, the relationship between bacteriospermia and leukocytospermia as well as their specific impact on functional sperm parameters and reproductive outcome variables such as fertilization or clinical pregnancy must be further investigated. The aim of this narrative review is to provide an update on the current knowledge on leukocytospermia and bacteriospermia and their impact on male fertility.

Decreased Ubiquitination and Acetylation of Histones 3 and 4 Are Associated with Obesity-Induced Disorders of Spermatogenesis in Mice

BACKGROUND

Obesity, a chronic metabolic disorder, is related to cardiovascular diseases, diabetes, cancer, and reproductive disorders. The relationship between obesity and male infertility is now well recognized, but the mechanisms involved are unclear. We aimed to observe the effect of obesity on spermatogenesis and to investigate the role of histone ubiquitination and acetylation modifications in obesity-induced spermatogenesis disorders.

METHODS

Thirty male C57BL/6J mice were randomly divided into two groups. The control group was fed with a general maintenance diet (12% fat), while a high-fat diet (HFD) group was fed with 40% fat for 10 weeks; then, they were mated with normal females. The fertility of male mice was calculated, testicular and sperm morphology were observed, and the expression levels of key genes and the levels of histone acetylation and ubiquitination modification during spermatogenesis were detected.

RESULTS

The number of sperm was decreased, as well as the sperm motility, while the number of sperm with malformations was increased. In the testes, the mRNA and protein expression levels of gonadotropin-regulated testicular RNA helicase (GRTH/DDX25), chromosome region maintenance-1 protein (CRM1), high-mobility group B2 (HMGB2), phosphoglycerate kinase 2 (PGK2), and testicular angiotensin-converting enzyme (tACE) were decreased. Furthermore, obesity led to a decrease in ubiquitinated H2A (ubH2A) and reduced levels of histone H3 acetylation K18 (H3AcK18) and histone H4 acetylation K5, K8, K12, and K16 (H4tetraAck), which disrupted protamine 1 (Prm1) deposition in testis tissue.

CONCLUSION

These results suggest that low levels of histone ubiquitination and acetylation are linked with obesity-induced disorders during spermatogenesis, contributing to a better understanding of obesity-induced damage to male reproduction.

Redox Homeostasis and Nrf2-Regulated Mechanisms Are Relevant to Male Infertility

Infertility represents a significant global health challenge, affecting more than 12% of couples worldwide, and most cases of infertility are caused by male factors. Several pathological pathways are implicated in male infertility. The main mechanisms involved are driven by the loss of reduction-oxidation (redox) homeostasis and the resulting oxidative damage as well as the chronic inflammatory process. Increased or severe oxidative stress leads to sperm plasma membrane and DNA oxidative damage, dysregulated RNA processing, and telomere destruction. The signaling pathways of these molecular events are also regulated by Nuclear factor-E2-related factor 2 (Nrf2). The causes of male infertility, the role of oxidative stress in male infertility and the Keap1-Nrf2 antioxidant pathway are reviewed. This review highlights the regulatory role of Nrf2 in the balance between oxidants and antioxidants as relevant mechanisms to male fertility. Nrf2 is involved in the regulation of spermatogenesis and sperm quality. Establishing a link between Nrf2 signaling pathways and the regulation of male fertility provides the basis for molecular modulation of inflammatory processes, reactive oxygen species generation, and the antioxidant molecular network, including the Nrf2-regulated antioxidant response, to improve male reproductive outcomes.

Emerging Role of Eruca sativa Mill. in Male Reproductive Health

A growing interest has been drawn to the use of traditional medicinal plants for the treatment of human diseases and, in particular, infertility and reproductive toxicity associated with environmental factors. The Mediterranean basin area is a recognized source of plant species with therapeutic interest. In this frame, Eruca sativa (ES) is an annual edible plant and a member of the Brassicaceae family. A relatively large number of studies, focusing on the biological effects of the extract from the leaves of ES on in vitro and in vivo models of disease, have been published in recent years. The present narrative review aims to analyze the phytochemical constituents, traditional uses, possible pharmacological activities, and recognized effects of ES on male reproductive outcomes. Available investigations have revealed the presence of a number of compounds with antioxidant properties, such as polyphenols, glucosinolates, flavonoids, and carotenoids in extracts from ES. Based on the chemical and pharmacological characteristics of the aforementioned compounds, we show that ES has possible preventive properties and therapeutic uses, especially in the functional derangements of the male reproductive system.

Deferasirox Targeting Ferroptosis Synergistically Ameliorates Myocardial Ischemia Reperfusion Injury in Conjunction With Cyclosporine A

BACKGROUND

Ferroptosis, an iron-dependent form of regulated cell death, is a major cell death mode in myocardial ischemia reperfusion (I/R) injury, along with mitochondrial permeability transition-driven necrosis, which is inhibited by cyclosporine A (CsA). However, therapeutics targeting ferroptosis during myocardial I/R injury have not yet been developed. Hence, we aimed to investigate the therapeutic efficacy of deferasirox, an iron chelator, against hypoxia/reoxygenation-induced ferroptosis in cultured cardiomyocytes and myocardial I/R injury.

METHODS AND RESULTS

The effects of deferasirox on hypoxia/reoxygenation-induced iron overload in the endoplasmic reticulum, lipid peroxidation, and ferroptosis were examined in cultured cardiomyocytes. In a mouse model of I/R injury, the infarct size and adverse cardiac remodeling were examined after treatment with deferasirox, CsA, or both in combination. Deferasirox suppressed hypoxia- or hypoxia/reoxygenation-induced iron overload in the endoplasmic reticulum, lipid peroxidation, and ferroptosis in cultured cardiomyocytes. Deferasirox treatment reduced iron levels in the endoplasmic reticulum and prevented increases in lipid peroxidation and ferroptosis in the I/R-injured myocardium 24 hours after I/R. Deferasirox and CsA independently reduced the infarct size after I/R injury to a similar degree, and combination therapy with deferasirox and CsA synergistically reduced the infarct size (infarct area/area at risk; control treatment: 64±2%; deferasirox treatment: 48±3%; CsA treatment: 48±4%; deferasirox+CsA treatment: 37±3%), thereby ameliorating adverse cardiac remodeling on day 14 after I/R.

CONCLUSIONS

Combination therapy with deferasirox and CsA may be a clinically feasible and effective therapeutic approach for limiting I/R injury and ameliorating adverse cardiac remodeling after myocardial infarction.

Toxicity of Beauty Salon Effluents Contaminated with Hair Dye on Aquatic Organisms

Cosmetic residues have been found in water resources, especially trace elements of precursors, couplers, and pigments of hair dyes, which are indiscriminately disposed of in the sewage system. These contaminants are persistent, bioactive, and bioaccumulative, and may pose risks to living beings. Thus, the present study assessed the ecotoxicity of two types of effluents generated in beauty salons after the hair dyeing process. The toxicity of effluent derived from capillary washing with water, shampoo, and conditioner (complete effluent-CE) and effluent not associated with these products (dye effluent-DE) was evaluated by tests carried out with the aquatic organisms Artemia salina, Daphnia similis, and Danio rerio. The bioindicators were exposed to pure samples and different dilutions of both effluents. The results showed toxicity in D. similis (CE50 of 3.43% and 0.54% for CE and DE, respectively); A. salina (LC50 8.327% and 3.874% for CE and DE, respectively); and D. rerio (LC50 of 4.25-4.59% and 7.33-8.18% for CE and DE, respectively). Given these results, we can infer that hair dyes, even at low concentrations, have a high toxic potential for aquatic biota, as they induced deleterious effects in all tested bioindicators.

Role of oxidative stress in male infertility

Abstract

Infertility affects millions of couples worldwide. Oxidative stress (OS) causes peroxidation of lipids and damage to spermatozoa, thus, reducing the quality of seminal parameters. In addition, the differences in the levels of antioxidants and reactive oxygen species (ROS) caused by intrinsic and extrinsic variables linked to lifestyle, diet, genetics, and OS also contribute to male infertility. High levels of ROS result in sperm damage of sperm parameters due to lipid peroxidation and oxidation of proteins. Other significant causes of ROS include changes in sex hormone levels, sperm DNA damage, including mutations, and immature spermatozoa. Treating the root causes of OS, by changing one's lifestyle, as well as antioxidant therapy, may be helpful strategies to fight OS-related infertility. However, the determination of male infertility induced by OS is currently a challenge in the field of reproductive health research. This review intends to describe the role of oxidative stress on male infertility and the current understanding of its management.

Lay summary

The inability to conceive affects many couples globally. Oxidative stress refers to imbalances between different oxygen species which can lead to male fertility problems by damaging sperm and semen. Oxidative stress may be caused by several factors, including diets high in fats, sugars and processed foods, lifestyle (including smoking, alcohol consumption and having a sedentary lifestyle), and genetics. Treatment that focuses on the root cause may help combat male infertility. However, there is currently no consensus on the best way to treat male fertility problems, particularly those associated with oxidative stress. This paper describes the role of oxidative stress on male infertility and discusses the current techniques employed in treating male fertility issues.

Male infertility and the human microbiome

The historical belief in urology was that the genitourinary system should be sterile in a normal, healthy, asymptomatic adult. This idea was perpetuated for decades until research revealed a diverse microbiota existing in human anatomical niches that contributed to both human health and disease processes. In recent years, the search for an etiology and modifiable risk factors in infertility has turned to the human microbiome as well. Changes in the human gut microbiome have been associated with changes in systemic sex hormones and spermatogenesis. Certain microbial species are associated with higher levels of oxidative stress, which may contribute to an environment higher in oxidative reactive potential. Studies have demonstrated a link between increased oxidative reactive potential and abnormal semen parameters in infertile men. It has also been hypothesized that antioxidant probiotics may be able to correct an imbalance in the oxidative environment and improve male fertility, with promising results in small studies. Further, the sexual partner's microbiome may play a role as well; studies have demonstrated an overlap in the genitourinary microbiomes in sexually active couples that become more similar after intercourse. While the potential applications of the microbiome to male fertility is exciting, there is a need for larger studies with uniform microbial sequencing procedures to further expand this topic.

Human Sperm as an In Vitro Model to Assess the Efficacy of Antioxidant Supplements during Sperm Handling: A Narrative Review

Spermatozoa are highly differentiated cells that produce reactive oxygen species (ROS) due to aerobic metabolism. Below a certain threshold, ROS are important in signal transduction pathways and cellular physiological processes, whereas ROS overproduction damages spermatozoa. Sperm manipulation and preparation protocols during assisted reproductive procedures-for example, cryopreservation-can result in excessive ROS production, exposing these cells to oxidative damage. Thus, antioxidants are a relevant topic in sperm quality. This narrative review focuses on human spermatozoa as an in vitro model to study which antioxidants can be used to supplement media. The review comprises a brief presentation of the human sperm structure, a general overview of the main items of reduction-oxidation homeostasis and the ambivalent relationship between spermatozoa and ROS. The main body of the paper deals with studies in which human sperm have been used as an in vitro model to test antioxidant compounds, including natural extracts. The presence and the synergic effects of different antioxidant molecules could potentially lead to more effective products in vitro and, in the future, in vivo.

Role of Macroautophagy in Mammalian Male Reproductive Physiology

Physiologically, autophagy is an evolutionarily conserved and self-degradative process in cells. Autophagy carries out normal physiological roles throughout mammalian life. Accumulating evidence shows autophagy as a mechanism for cellular growth, development, differentiation, survival, and homeostasis. In male reproductive systems, normal spermatogenesis and steroidogenesis need a balance between degradation and energy supply to preserve cellular metabolic homeostasis. The main process of autophagy includes the formation and maturation of the phagophore, autophagosome, and autolysosome. Autophagy is controlled by a group of autophagy-related genes that form the core machinery of autophagy. Three types of autophagy mechanisms have been discovered in mammalian cells: macroautophagy, microautophagy, and chaperone-mediated autophagy. Autophagy is classified as non-selective or selective. Non-selective macroautophagy randomly engulfs the cytoplasmic components in autophagosomes that are degraded by lysosomal enzymes. While selective macroautophagy precisely identifies and degrades a specific element, current findings have shown the novel functional roles of autophagy in male reproduction. It has been recognized that dysfunction in the autophagy process can be associated with male infertility. Overall, this review provides an overview of the cellular and molecular basics of autophagy and summarizes the latest findings on the key role of autophagy in mammalian male reproductive physiology.

The Dual Role of Oxidants in Male (In)fertility: Every ROSe Has a Thorn

The role of oxidative stress (OS) in male infertility as a primary etiology and/or concomitant cause in other situations, such as inflammation, varicocele and gonadotoxin effects, is well documented. While reactive oxygen species (ROS) are implicated in many important roles, from spermatogenesis to fertilization, epigenetic mechanisms which are transmissible to offspring have also recently been described. The present review is focused on the dual aspects of ROS, which are regulated by a delicate equilibrium with antioxidants due to the special frailty of spermatozoa, in continuum from physiological condition to OS. When the ROS production is excessive, OS ensues and is amplified by a chain of events leading to damage of lipids, proteins and DNA, ultimately causing infertility and/or precocious pregnancy termination. After a description of positive ROS actions and of vulnerability of spermatozoa due to specific maturative and structural characteristics, we linger on the total antioxidant capacity (TAC) of seminal plasma, which is a measure of non-enzymatic non-proteic antioxidants, due to its importance as a biomarker of the redox status of semen; the therapeutic implications of these mechanism play a key role in the personalized approach to male infertility.

Isoliquiritigenin ameliorates paroxetine-induced sexual dysfunction in male albino mice

Paroxetine (PRX), a widely prescribed antidepressant, often leads to sexual dysfunction. The available management options such as sildenafil (SDF), are associated with side effects. The present study investigates the fertility-boosting properties of isoliquiritigenin (ISL) on PRX-induced sexual dysfunction in male mice. We allocated fertile mice into six different groups (n = 5): group I- DMSO; group II- PRX; group III- co-administered PRX and SDF; group IV- ISL alone; group V- co-administered PRX and ISL (low dose); and, group VI- co-administered PRX and ISL (high dose). 14 days post treatment, animals were sacrificed, and the weights of the testis and epididymis were evaluated. Furthermore, sperm parameters, testicular and epididymal antioxidant levels, serum testosterone and nitric oxide (NO) levels, histoarchitecture of testis and epididymis, and markers of cellular toxicity were assessed. Results revealed that the PRX administration reduced organ weights, sperm count, intact acrosome, catalase (CAT), superoxide dismutase (SOD), glutathione (GSH), serum testosterone, and NO levels, and increased sperm abnormalities and MDA levels (a biomarker for lipid peroxidation). Additionally, we observed damage in the testis and epididymis. The toxicity biomarker study revealed a higher concentration of SGOT, SGPT, and ALP enzymes in the PRX-treated group. However, the co-administration of PRX with ISL ameliorated the adverse effect of PRX on the parameters mentioned above. The PRX+ISL (high) results were almost at par with the PRX+SDF group. The group that received ISL alone showed overall improvements. In conclusion, our comprehensive panel of tests indicates that ISL could be helpful in managing sexual dysfunction.

Differences of semen microbiota among breeding boars with different reproductive ages

In this study, we investigated 18 healthy and fertile Duroc boars, dividing them into two groups based on their reproductive age: 9 boars aged 18 mo and 9 boars aged 36 mo. Prior to semen sampling, all boars were raised together under identical management conditions for a period of 3 mo. Our findings revealed that older boars exhibited lower sperm motility and a higher proportion of abnormal sperm morphology compared to younger boars. Furthermore, older boars demonstrated lower anti-oxidant capacity in their semen, as indicated by elevated levels of malondialdehyde and decreased levels of superoxide dismutase and glutathione peroxidase. Microbiota analysis utilizing the 16S rRNA technique showed that the semen microbiota of older boars had reduced alpha-diversity and beta-diversity in comparison to younger boars. We identified the Streptococcus genus and Streptococcus gallolyticus subsp macedonicus species served as biomarkers for semen from younger breeding boars, while the Bacteroides pyogenes species as a biomarker for semen from older breeding boars. Additionally, the semen from older boars exhibited a higher abundance of Aerococcus, Gallicola, Ulvibacter, and Proteiniphilum compared to younger boars. Spearman correlation analysis showed that these four bacteria were negatively correlated with semen quality. The abundance of Gallicola and Proteiniphilum were negatively correlated with semen anti-oxidant capacity. Additionally, the reduction of semen anti-oxidant capacity was correlated to the decrease of semen quality. Based on these findings, we concluded that the semen of older boars contains a higher abundance of harmful bacteria, which contributes to the observed reduction in semen anti-oxidant capacity and overall semen quality in this group.

Unraveling the harmful effect of oxidative stress on male fertility: A mechanistic insight

Male infertility is a widely debated issue that affects males globally. There are several mechanisms involved. Oxidative stress is accepted to be the main contributing factor, with sperm quality and quantity affected by the overproduction of free radicals. Excess reactive oxygen species (ROS) cannot be controlled by the antioxidant system and, thus, potentially impact male fertility and hamper sperm quality parameters. Mitochondria are the driving force of sperm motility; irregularities in their function may lead to apoptosis, alterations to signaling pathway function, and, ultimately, compromised fertility. Moreover, it has been observed that the prevalence of inflammation may arrest sperm function and the production of cytokines triggered by the overproduction of ROS. Further, oxidative stress interacts with seminal plasma proteomes that influence male fertility. Enhanced ROS production disturbs the cellular constituents, particularly DNA, and sperms are unable to impregnate the ovum. Here, we review the latest information to better understand the relationship between oxidative stress and male infertility, the role of mitochondria, the cellular response, inflammation and fertility, and the interaction of seminal plasma proteomes with oxidative stress, as well as highlight the influence of oxidative stress on hormones; collectively, all of these factors are assumed to be important for the regulation of male infertility. This article may help improve our understanding of male infertility and the strategies to prevent it.

Fertility in the aging male: a systematic review

The negative effect of advanced female age on fertility and offspring health is well understood. In comparison, much less is known about the implications of male age on fertility, with many studies showing conflicting results. Nevertheless, increasing evidence suggests that advanced paternal age has negative effects on sperm parameters, reproductive success, and offspring health. Herein, we summarize the current body of knowledge on this controversial topic, with the belief that this review will serve as a resource for the clinicians providing fertility counseling to couples with older male partners.

Characterization of the structural, oxidative, and immunological features of testis tissue from Zucker diabetic fatty rats

The purpose of this study was to characterize the testicular profile of Zucker diabetic fatty (ZDF) rats presenting with type 2 diabetes mellitus (DM2) in the absence or presence of obesity. To achieve this, testes were collected from 270-day-old male Wistar (n = 15), ZDF nonobese (n = 15), and ZDF obese rats (n = 16). Changes to the testicular structure were quantified morphometrically, while immunocytochemistry was employed to assess caspase-3 activity. Reactive oxygen species (ROS) production, fluctuations of major antioxidant molecules, and the extent of damage to the proteins and lipids were assessed in tissue lysates. Levels of selected interleukins (ILs) were determined by enzyme-linked immunosorbent assay. The results reveal significant alterations to the testicular structure accompanied by caspase-3 overexpression, particularly in ZDF obese rats. The most notable disruption of the oxidative balance, characterized by ROS overproduction, antioxidant deficiency, protein, and lipid deterioration was recorded in ZDF rats suffering from both DM2 and obesity. Accordingly, the highest concentrations of pro-inflammatory IL-1, IL-6, and IL-18 accompanied by reduced levels of the anti-inflammatory IL-10 were found in testicular tissue collected from ZDF obese rats. This study highlights the vulnerability of male gonads to pathophysiological changes caused by hyperglycemia, which are further exacerbated by excessive adipose tissue.

Semen Quality in Males Suffering From COVID-19: A Pilot Study

Background It is well known that some viral infections may affect male fertility. Coronavirus disease (COVID-19) can lead to multiorgan damage through the angiotensin-converting enzyme-2 receptor, abundant in testicular tissue. However, little information is available regarding the shedding of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) in semen and its impact on spermatogenesis and fertility potential. We planned to investigate the presence of SARS-CoV-2 in the semen of COVID-19 males and to study the effect of COVID-19 on semen quality and sperm DNA fragmentation index. Material and method Thirty COVID-19 male patients aged 19-45 registered to AIIMS Patna hospital participated in the survey between October 2020 and April 2021. We conducted a real-time reverse transcriptase test on all the semen samples. Detailed semen analysis, including the sperm DNA Fragmentation Index, was done at first sampling that is during COVID-19. After 74 days of the first sampling, we obtained the second sampling and repeated all the above tests. Results All semen samples collected in the first and second sampling tested with real-time reverse transcription-polymerase chain reaction (RT-PCR) were negative for SARS-CoV-2. In the first sampling, semen volume, vitality, total motility, sperm concentration, total sperm count, % normal morphology, % cytoplasmic droplet, and fructose were significantly lower. In contrast, semen agglutination, % head defect, DNA Fragmentation Index, liquefaction time, semen viscosity, and leukocytes were increased. These findings were reversed at the second sampling but not to the optimum level. All these findings were statistically significant (p < 0.05 for all). Thus, COVID-19 negatively affects semen parameters, including sperm DNA fragmentation index. Conclusion Although we could not find SARS-CoV-2 in the semen, the semen quality remained poor until the second sampling. Assisted reproductive technology (ART) clinics and sperm banking facilities should consider assessing the semen of COVID-19 males and exclude men with a positive history of SARS-CoV-2 until their semen quality returns to normal.

Male Infertility Coexists with Decreased Sperm Genomic Integrity and Oxidative Stress in Semen Irrespective of Leukocytospermia

Our research was designed to verify the relationship between male infertility, basic semen characteristics (with respect to detailed sperm morphology), sperm DNA fragmentation (SDF), oxidation-reduction potential in semen (ORP), and leukocytospermia. The obtained results showed that infertile groups (with or without leukocytospermia) had significantly lower basic semen characteristics and higher SDF, raw ORP, and static ORP (sORP) than fertile controls. The thresholds of 13% SDF (AUC = 0.733) and 1.40 sORP (AUC = 0.857) were predictive values for discriminating infertile from fertile men. In infertile groups, a higher prevalence and risk for >13% SDF and >1.40 sORP were revealed. Unexpectedly, leukocytospermic subjects had lower sORP, prevalence, and risk for >1.40 sORP than leukocytospermic-negative men. These groups did not differ in SDF and raw ORP. Both SDF and sORP negatively correlated with basic semen parameters but positively correlated with sperm head and midpiece defects. sORP positively correlated with sperm tail defects, immature sperm cells with excess residual cytoplasm, and SDF. In turn, raw ORP negatively correlated with sperm count but positively correlated with SDF and sORP. These findings indicate that (1) there is a relationship between male infertility, SDF, and OS in semen; (2) in infertile men, there is a clinically significant risk of SDF and OS irrespective of leukocytospermia; and (3) the assessment of SDF and oxidative stress should be independent of leukocytospermia.

Bacteriospermia - A formidable player in male subfertility

Bacterial colonization of male reproductive tissues, cells, and fluids, and the subsequent impact of bacteria on the sperm architecture, activity, and fertilizing potential, has recently gained increased attention from the medical and scientific community. Current evidence strongly emphasizes the fact that the presence of bacteria in semen may have dire consequences on the resulting male fertility. Nevertheless, the molecular basis underlying bacteriospermia-associated suboptimal semen quality is sophisticated, multifactorial, and still needs further understanding. Bacterial adhesion and subsequent sperm agglutination and immobilization represent the most direct pathway of sperm-bacterial interactions. Furthermore, the release of bacterial toxins and leukocytic infiltration, associated with a massive outburst of reactive oxygen species, have been repeatedly associated with sperm dysfunction in bacteria-infested semen. This review serves as a summary of the present knowledge on bacteriospermia-associated male subfertility. Furthermore, we strived to outline the currently available methods for assessing bacterial profiles in semen and to outline the most promising strategies for the prevention and/or management of bacteriospermia in practice.

Association between Seminal Oxidation-Reduction Potential and Sperm DNA Fragmentation-A Meta-Analysis

Seminal oxidative stress and sperm DNA damage are potential etiologies of male factor infertility. The present study aims to evaluate the relationship between oxidation-reduction potential (ORP), a measure of oxidative stress, and sperm DNA fragmentation (SDF) by conducting a systematic review and meta-analysis of relevant clinical data. A literature search was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The COVIDENCE tool was used to screen and identify studies evaluating seminal ORP and SDF. Studies (n = 7) that measured seminal ORP and SDF of 3491 semen samples were included in the analysis. The fixed-effects model revealed a significant pooled correlation coefficient (r = 0.24; p < 0.001) between seminal ORP and SDF. Furthermore, subgroup analyses indicated that the pooled correlation coefficient between ORP and sperm chromatin dispersion (SCD) assay was less than other SDF assays (0.23 vs. 0.29). There was a moderate level of heterogeneity (I2 = 42.27%) among the studies, indicating a lack of publication bias. This is the first meta-analysis to reveal a positive correlation between seminal ORP and SDF. Furthermore, this study indicates the role of oxidative stress in the development of sperm DNA damage and thus warrants prospectively exploring the clinical value of these sperm function tests.

Possible Implications of Bacteriospermia on the Sperm Quality, Oxidative Characteristics, and Seminal Cytokine Network in Normozoospermic Men

This study focused on the identification of bacterial profiles of semen in normozoospermic men and their possible involvement in changes to the sperm structural integrity and functional activity. Furthermore, we studied possible fluctuations of selected cytokines, oxidative markers, and antibacterial proteins as a result of bacterial presence in the ejaculate. Sperm motility was assessed with computer-assisted sperm analysis, while sperm apoptosis, necrosis and acrosome integrity were examined with fluorescent methods. Reactive oxygen species (ROS) generation was quantified via luminometry, sperm DNA fragmentation was evaluated using the TUNEL protocol and chromatin-dispersion test, while the JC-1 assay was applied to evaluate the mitochondrial membrane potential. Cytokine levels were quantified with the biochip assay, whilst selected antibacterial proteins were quantified using the ELISA method. The predominant species identified by the matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry were Staphylococcus hominis, Staphylococcus capitis and Micrococcus luteus. The results revealed that the sperm quality decreased proportionally to the increasing bacterial load and occurrence of conditionally pathogenic bacteria, including Enterococcus faecalis, Staphylococcus aureus and Escherichia coli. Antimicrobial susceptibility tests revealed a substantial resistance of randomly selected bacterial strains to ampicillin, vancomycin, tobramycin, and tetracycline. Furthermore, an increased bacterial quantity in semen was accompanied by elevated levels of pro-inflammatory cytokines, including interleukin-1, interleukin-2, interleukin-6, tumor necrosis factor alpha as well as ROS overproduction and lipid peroxidation of the sperm membranes. Our results suggest that semen quality may be notably affected by the bacterial quantity as well as quality. It seems that bacteriospermia may be associated with inflammatory processes, oxidative stress, sperm structural deterioration, and a subsequent risk for the development of subfertility, even in normozoospermic males.

Lipid Signaling During Gamete Maturation

Cell lipids are differentially distributed in distinct organelles and within the leaflets of the bilayer. They can further form laterally defined sub-domains within membranes with important signaling functions. This molecular and spatial complexity offers optimal platforms for signaling with the associated challenge of dissecting these pathways especially that lipid metabolism tends to be highly interconnected. Lipid signaling has historically been implicated in gamete function, however the detailed signaling pathways involved remain obscure. In this review we focus on oocyte and sperm maturation in an effort to consolidate current knowledge of the role of lipid signaling and set the stage for future directions.

Bacteriospermia and Male Infertility: Role of Oxidative Stress

Male infertility is one of the major challenging and prevalent diseases having diverse etiologies of which bacteriospermia play a significant role. It has been estimated that approximately 15% of all infertility cases are due to infections caused by uropathogens and in most of the cases bacteria are involved in infection and inflammation leading to the development of bacteriospermia. In response to bacterial load, excess infiltration of leukocytes in the urogenital tract occurs and concomitantly generates oxidative stress (OS). Bacteria may induce infertility either by directly interacting with sperm or by generating reactive oxygen species (ROS) and impair sperm parameters such as motility, volume, capacitation, hyperactivation. They may also induce apoptosis leading to sperm death. Acute bacteriospermia is related with another clinical condition called leukocytospermia and both compromise male fertility potential by OS-mediated damage to sperm leading to male infertility. However, bacteriospermia as a clinical condition as well as the mechanism of action remains poorly understood, necessitating further research in order to understand the role of individual bacterial species and their impact in male infertility.

Positive Effect of a New Combination of Antioxidants and Natural Hormone Stimulants for the Treatment of Oligoasthenoteratozoospermia

Oligoasthenoteratozoospermia (OAT) accounts for about 90% of male infertility; in many cases this disorder may be associated with oxidative stress, a condition that decreases the success of fertilization. Therefore, the empirical treatment of male infertility is often based on the use of antioxidants. The aim of the present study was to assess the effectiveness of three months’ administration of a new nutraceutical preparation on hormone profile, sperm parameters and fertilization capability in men undergoing in vitro fertilization (IVF). A total of 36 OAT patients were daily treated for 3 months with a dose of a formulation containing: Inositol, L-Carnitine, Vitamins C, D, E, Coenzyme Q10 and Selenium. Selected parameters were analysed before (T0) and after (T1) treatment, and IVF outcomes were evaluated. We observed an improvement of sperm concentration, motility, morphology and vitality; blood level of testosterone also showed an increase. A significant increase of fertilization rate was detected in 14 couples, whose male partner were treated with the nutraceutical preparation. The present results indicate that a formulation containing antioxidant and energy supply substances was effective in the treatment of sperm alterations and led to significant recovery of fertilizing capacity.

Effects of leukocytospermia on the outcomes of assisted reproductive technology

Leukocytospermia is one of the common causes of male infertility, and its effects on the clinical outcomes of assisted reproduction are controversial. There are no recommendations for the management of leukocytospermia in cases of assisted reproductive technology (ART). To investigate the impact of leukocytospermia on ART, we retrospectively compared the clinical outcomes in ART couples with or without leukocytospermia and further analysed the impact of the insemination method itself by split insemination treatment in ART couples with leukocytospermia. In this study, leukocytospermia was detected in 133 patients, namely 63 in the conventional in vitro fertilization (IVF) group, 38 in the intracytoplasmic sperm injection (ICSI) group and 32 in the split insemination group. Leukocytospermia has a negative influence on the parameters of semen samples; however, leukocytospermia did not affect the clinical outcomes of IVF or ICSI. Different insemination methods did not affect the fertilization, clinical pregnancy or live birth rates. In the split insemination study, no significant differences in clinical pregnancy and live birth rates between the IVF and ICSI groups were found; however, the numbers of two pronuclei (2PN), available embryos and good‐quality embryos in the ICSI group were higher than those in the IVF group. Leukocytospermia may be a risk factor affecting semen parameters, and more attention should be given to IVF insemination. Leukocytospermia has no significant negative effect on the outcomes of ART. ICSI may obtain better embryos than IVF, but it cannot improve the clinical pregnancy and live birth rates.

Deciphering the Nexus Between Oxidative Stress and Spermatogenesis: A Compendious Overview

Oxidative stress (OS) and reactive oxygen species (ROS) are one of the main reasons for the multifactorial concern - male infertility. ROS are active components of cellular metabolism that are intrinsic to cellular functioning and are present at minimal and unreactive levels in normal cells. They are an integral component of the sperm developmental physiology, capacitation, and function. As said "anything in excess is poison," so is the case with ROS. These, when produced in excess to the antioxidants present in the seminal plasma, cause multiple malformations during the process of spermatogenesis such as lipid peroxidation, interfere with capacitation, sperm DNA fragmentation and damage to the membrane of the sperm which in turn reduces the motility of the sperm and its ability to fuse with the oocyte. Exposure of spermatozoa to oxidative stress is a major causative agent of male infertility. Thus, a delicate balance between the beneficial and detrimental effects of ROS for proper functions is of utter importance. In this chapter, the influence of ROS in OS which is a key player in male infertility along with the diagnosis, available treatment, and prevention of extensive ROS buildup within the spermatozoa are highlighted.

Sperm quality parameters and oxidative stress: Exploring correlation in fluoride-intoxicated rats

Background:

Assessment of male fertility needs evaluation of sperm quality parameters, namely sperm count, viability, motility and morphology.

Aims:

The present study aimed to analyse and correlate oxidative stress with sperm quality parameters.

Settings and Design:

The male Wistar albino rats, weighing between 100 and 150 g, were employed in the present study under the Committee for the Purpose of Control and Supervision of Experiments on Animals guidelines with ethical clearance from the Institutional Ethical Committee. These rats were categorised into four groups with six rats in each as control and test animals.

Materials and Methods:

Young male Wistar albino rats, weighing between 100 and 150 g, were divided into four groups of six rats each. The first group of rats served as control (n = 6) and was maintained under normal laboratory condition and was provided with clean drinking water, whereas rats in the second (n = 6), third (n = 6) and fourth (n = 6) groups were orally intubated with sodium fluoride of 100 ppm, 200 ppm and 300 ppm, respectively, for 40 days.

Statistical Analysis Used:

After the treatment period of 40 days, animals were sacrificed and alterations in sperm quality parameters were analysed by complete randomised design SAS 9.4 and Statistical Package for the Social Sciences (SPSS) IBM 17 and judged significant if P < 0.05.

Results:

In the experiment, a negative correlation emerged between sperm motility, viability, count versus malondialdehyde (MDA) levels, whereas the level of MDA has a positive correlation with sperm abnormalities. Sperm motility, viability and count were positively correlated with activities of superoxide dismutase and catalase, whereas decreased activities of antioxidants were related to increased sperm morphological abnormalities.

Conclusion:

These results suggest that MDA causes a decline in sperm motility, count and viability and an increase in morphological abnormalities via oxidative damage of membrane lipids.

A Comparative Analysis of the Altered Levels of Human Seminal Plasma Constituents as Contributing Factors in Different Types of Male Infertility

(1) Background: The relationships between the biochemical and immunological components in seminal plasma and their physiological effects on male reproductive system have been underreported. In this study, we evaluated the potential of several seminal plasma biochemical and immunological markers in the pathophysiological developments of the infertile male patients. The study was designed to identify and assess different markers that may be associated with semen functions in different types of male infertility. (2) Methods: A total of 50 infertile male patients who underwent checkup for fertility assessment and 50 fertile controls were included in this study. The complete medical history of each recruited participant was reviewed. The infertile sub-groups (non-obstructive azoospermia (NOA), asthenozoospermia (AS), normozoospermic infertile (NI), and oligozoospermia (OZ)) were characterized based on sperm motility and concentration, while NI patients were included after a thorough check up of their female partners as well. We investigated each sample for 21 different analytes, enzymes, trace elements, and immunological markers to find crucial markers posing as contributing factors to a specific type of male infertility. (3) Results: The levels of 15 out of 21 markers, assayed from the seminal plasma of infertile males, were significantly altered in comparison to fertile controls (p < 0.05). For the first time, microprotein levels were also analyzed. The presence of monocytes, lymphocytes, and granulocytes was limited to semen from NOA patients, while a significant increase in the level of platelets was observed in AS. Hierarchical clustering and ROC-AUC analysis identified the three most significant markers (zinc, LDH, and TG) for the healthy control group and asthenozoospermic group (AUC, of 0.92 and 0.81, respectively). (4) Conclusions: The altered levels of biochemical and immunological markers in seminal plasma might be associated with the different male infertility profiles and could be required for the sperm metabolism and maintenance. However, a larger sample size and follow up analysis is required for establishing the hypothesized panel of markers as biomarkers at clinical stage.

Ameliorative effect of hesperidin on streptozotocin-diabetes mellitus-induced testicular DNA damage and sperm quality degradation in Sprague-Dawley rats

This study aimed to investigate the effect of hesperidin on reproductive damage caused by diabetes mellitus. A total of 24 adult male rats were divided into four groups: control group, hesperidin group, diabetes mellitus group, and diabetes mellitus + hesperidin group. The study was conducted for 4 weeks. At the end of the study, the rats were sacrificed and testicular oxidative stress markers (MDA, GSH, GSH-Px, SOD, and CAT), DNA damage in testes (8-OHdG), and routine sperm parameters were evaluated. According to the results of the study, most of the parameters were similar in the control and hesperidin groups but CAT activity in the hesperidin group was statistically higher than the control group. Also, diabetes mellitus (DM) significantly increased MDA levels and decreased enzymatic antioxidant (GSH-Px, SOD, CAT) activities and nonenzymatic (GSH) antioxidant levels. On the other hand, hesperidin supplementation significantly decreased oxidative stress and increased enzymatic antioxidant activities and nonenzymatic antioxidant levels due to the antioxidant effect. Also, DM increased DNA damage levels in testicular tissue and hesperidin supplementation significantly decreased DNA damage levels in testes of diabetic male rats. Besides, sperm motility significantly decreased while abnormal sperm rate and dead sperm rate were significantly increased in diabetic rats. Hesperidin supplementation significantly reduced these side effects in diabetic rats. In conclusion, hesperidin supplementation could be beneficial for decreasing the side effects on the male reproductive system caused by DM in rats. PRACTICAL APPLICATIONS: Diabetes is an important metabolic disease, affecting quality of life and fertility. Hesperidin has an antioxidant effect and has a potential protective effect on reproductive toxicity in diabetic male rats. Hesperidin decreased oxidative stress, and DNA damage in testis resulted from hyperglycemia and improved sperm quality in diabetic rats. The hesperidin supplementation could be a good strategy to protect male fertility in diabetic patients.

Soursop juice enhanced seminal antioxidant defence and semen quality of rabbit bucks in extremely dry climatic condition of Southwestern Nigeria

Heat induced stress associated with dry climatic conditions in the tropics does have adverse effects reproduction in rabbits, and this in-turn impacts negatively on the income of rabbit farmers. However, natural products might prove to be a reliable, safe and cheap remedy for ameliorating reproductive such anomalies in rabbits. The potential of soursop for mitigating heat induced reproductive deficiency in rabbit bucks was investigated during the peak of dry climatic conditions in southwestern Nigeria. Sixty mixed breed (New Zealand white x Chinchilla) adult rabbit bucks were allotted to five treatments of four replicates (3 bucks per replicate) each in a completely randomized design. Soursop (Annona muricata) fruit was processed into juice using standard procedures and was designated as soursop juice. The juice was administered orally daily per kg body weight (BW), 0.55ml/kgBW distilled water (control), 0.55 ml/kgBW soursop juice, 1.11 ml/kgBW soursop juice, 1.67 ml/kgBW soursop juice and 2.22 ml/kgBW soursop juice to designated treatments 1 to 5, respectively for 56 days. Semen samples were collected with an improvised artificial vagina on the 28th and 56th day of the study, semen quality and seminal oxidative status were evaluated using standard procedures. Results showed that rabbit buck exposed to heat stress had lower semen quality, seminal antioxidants and increased seminal lipid peroxidation. However, the consumption of soursop juice lowered lipid peroxidation and enhanced (p < 0.05) antioxidant production in the seminal fluid of heat-stressed bucks than bucks on control group. Bucks' semen quality and antioxidant status peaks in heat-stressed bucks gavaged 2.22 ml/kgBW soursop juice and gives 100% recovery from the effects of heat induced stress. It can be concluded that 2.22 ml/kgBW soursop juice administered for 56 days did enhance spermatozoa quality and mitigated lipid peroxidation by improving antioxidant capacity of male rabbits in a dose dependent manner on extremely dry climatic conditions.

Complementary effects of coenzyme Q10 and Lepidium sativum supplementation on the reproductive function of mice: An experimental study

Background

Coenzyme Q10 (CoQ10) and Lepidium sativum (LS) have therapeutic effects on infertility.

Objective

To evaluate the combined effects of LS and CoQ10 on reproductive function in adult male NMRI mice.

Materials and Methods

Eighty three-months-old male mice (35–40 gr) were divided into four groups (n = 10/each): control (treated with water), CoQ10-treated (200, 300, and 400 mg/kg/body weight), LS-treated (200, 400, 600 mg/kg/body weight), and co-treated (LS [600 mg/kg/body weight] + CoQ10 [200 mg/kg/body weight]) groups. Serum testosterone, luteinizing hormone, follicle-stimulating hormone, and gonadotropin realizing hormone (GnRH) levels were measured using ELISA method. The sperm quality was assessed using Sperm Class AnalyzerⓇ (SCA) CASA system and GnRH mRNA expression levels were evaluated by real-time polymerase chain reaction.

Results

The number of sniffing and following behavior was significantly higher in LS-treated (400 and 600 mg/ml/body weight) groups than the control group (p = 0.0007 and p = 0.0010, respectively). The number of mounting and coupling behaviors was significantly higher in the CoQ10 (300 and 400 mg/ml/body weight)-treated animals than the control group (p = 0.0170 and p = 0.0006, respectively). Co-treatment of CoQ10 (200 mg/ml/body weight) and LS (600 mg/ml/body weight) significantly increased all aspects of sexual behaviors as well as the levels of serum testosterone (p = 0.0011), luteinizing hormone (p = 0.0062), and follicle-stimulating hormone (p = 0.0001); sperm viability (p = 0.0300) and motility (p = 0.0010); and GnRH mRNA levels (p = 0.0016) compared to the control group.

Conclusion

The coadministration of CoQ10 and LS significantly improves the activity of the hypothalamic-pituitary-gonadal axis and enhances the reproductive parameters in adult male mice.

Sperm Lipid Markers of Male Fertility in Mammals

Sperm plasma membrane lipids are essential for the function and integrity of mammalian spermatozoa. Various lipid types are involved in each key step within the fertilization process in their own yet coordinated way. The balance between lipid metabolism is tightly regulated to ensure physiological cellular processes, especially referring to crucial steps such as sperm motility, capacitation, acrosome reaction or fusion. At the same time, it has been shown that male reproductive function depends on the homeostasis of sperm lipids. Here, we review the effects of phospholipid, neutral lipid and glycolipid homeostasis on sperm fertilization function and male fertility in mammals.

Sperm Motility, Oxidative Status, and Mitochondrial Activity: Exploring Correlation in Different Species

Sperm quality assessment is the first step for evaluating male fertility and includes the estimation of sperm concentration, motility, and morphology. Nevertheless, other parameters can be assessed providing additional information on the male reproductive potential. This study aimed to evaluate and correlate the oxidative status, mitochondrial functionality, and motility in spermatozoa of two marine invertebrate (Ciona robusta and Mytilus galloprovincialis) and one mammalian (Bos taurus) species. By combining fluorescent staining and spectrofluorometer, sperm oxidative status was evaluated through intracellular reactive oxygen species (ROS) and plasma membrane lipid peroxidation (LPO) analysis. Mitochondrial functionality was assessed through the mitochondrial membrane potential (MMP). In the three examined species, a negative correlation emerged between sperm motility vs ROS levels and LPO. Sperm motility positively correlated with MMP in bovine, whereas these parameters were not related in ascidian or even negatively related in mussel spermatozoa. MMP was negatively related to ROS and LPO levels in ascidians, only to LPO in bovine, and positively related in mussel spermatozoa. These results suggest that energy sources for sperm motility vary between species and that ROS causes a decline in sperm motility via oxidative damage of membrane lipids. Overall, this study validates the use of fluorescent probes in combination with spectrofluorometer as a simple and powerful methodology for supplementary evaluation of sperm quality shedding light on new potential quality markers and provided relevant information on sperm energetic metabolism.

Sperm Oxidative Stress during In Vitro Manipulation and Its Effects on Sperm Function and Embryo Development

Reactive oxygen species (ROS) generated at low levels during mitochondrial respiration have key roles in several signaling pathways. Oxidative stress (OS) arises when the generation of ROS exceeds the cell's antioxidant scavenging ability and leads to cell damage. Physiological ROS production in spermatozoa regulates essential functional characteristics such as motility, capacitation, acrosome reaction, hyperactivation, and sperm-oocyte fusion. OS can have detrimental effects on sperm function through lipid peroxidation, protein damage, and DNA strand breakage, which can eventually affect the fertility of an individual. Substantial evidence in the literature indicates that spermatozoa experiencing OS during in vitro manipulation procedures in human- and animal-assisted reproduction are increasingly associated with iatrogenic ROS production and eventual impairment of sperm function. Although a direct association between sperm OS and human assisted reproductive techniques (ART) outcomes after in vitro fertilization (IVF) and/or intracytoplasmic sperm injection (ICSI) is still a matter of debate, studies in animal models provide enough evidence on the adverse effects of sperm OS in vitro and defective fertilization and embryo development. This review summarized the literature on sperm OS in vitro, its effects on functional ability and embryo development, and the approaches that have been proposed to reduce iatrogenic sperm damage and altered embryonic development.

Cistanoside of Cistanche Herba ameliorates hypoxia-induced male reproductive damage via suppression of oxidative stress

Increasing evidence shows that hypoxia is a cause of male infertility, and hypoxia may be related to oxidative stress (OS). Cistanoside (Cis) is a phenylethanoid glycoside compound that can be extracted from Cistanches Herba and possesses various biological functions. This study aimed to investigate the protective effects of Cis on reproductive damage induced by hypoxia and explore the specific underlying mechanisms. Cell and animal hypoxia experimental models were constructed, and the protective effects of different subtypes of Cis on the male reproductive system were assessed both in vitro and in vivo. The results indicated that hypoxia significantly reduced the viability of GC-1 cells through cell cycle arrest and apoptosis activation, which were associated with increased OS. Moreover, Cis showed strong antioxidative effects both in vitro and in vivo, significantly restoring antioxidant enzyme activities and downregulating reactive oxygen species (ROS) levels while increasing cell viability and decreasing apoptosis. Importantly, the Cis subtypes (Cis-A, Cis-B, Cis-C and Cis-H) studied herein all showed certain antioxidant effects, among which the effects of Cis-B were the most significant. This study demonstrates that Cis markedly attenuates the harmful effects of hypoxia-induced OS by affecting antioxidant enzyme activities in testes and GC-1 cells.

Exogenous Factors Affecting the Functional Integrity of Male Reproduction

Natural processes along with increased industrial production and the irresponsible behavior of mankind have resulted in environmental pollution. Environmental pollutants can be categorized based on their characteristics and appearance into the following groups: physical, biological, and chemical. Every single one of them represents a serious threat to the male reproductive tract despite the different modes of action. Male gonads and gametes are especially vulnerable to the effect of exogenous factors; therefore, they are considered a reliable indicator of environmental pollution. The impact of xenobiotics or radiation leads to an irreversible impairment of fertility displayed by histological changes, modulated androgen production, or compromised spermatozoa (or germ cells) quality. The present article reviews the exogenous threats, male reproductive system, the mode of action, and overall impact on the reproductive health of humans and animals.

The microbiome of the infertile male

PURPOSE OF REVIEW

Contrary to historic dogma, many tissues and organs in the human body contain a resident population of bacteria, fungi, and viruses collectively known as the microbiome. The microbiome plays a role in both homeostatic symbiosis and also pathogenic dysbiosis in a wide array of diseases. Our understanding of the relationship between the microbiome and male factor infertility is in its infancy but is slowly evolving.

RECENT FINDINGS

Recent literature indicates that semen (and likely the testis) is not sterile and contains a distinct microbiome, and these changes in its composition are associated with alterations in semen quality and fertility status. Preliminary investigation indicates that manipulating the human microbiome may have implications in improving semen parameters and fertility.

SUMMARY

In this review, we describe relationships between the microbiome and the genitourinary system, discuss the prior work on the relationship among bacteriospermia, leukocytospermia and male factor infertility, and summarize the current literature utilizing 16s rRNA-based next-generation sequencing on the seminal and testicular microbiome. We explore the specific microbial taxa implicated in various aspects of spermatic dysfunction and introduce preliminary evidence for therapeutic approaches to alter the microbiome and improve fertility status.

Overtime expression of plasma membrane and mitochondrial function markers associated with cell death in human spermatozoa exposed to nonphysiological levels of reactive oxygen species

In many cell types, the potential of reactive oxygen species to induce death processes has been largely demonstrated. Studies in spermatozoa have associated the imbalance of reactive oxygen species and phosphatidylserine externalisation as an apoptosis marker. However, the lack of consensus about time effect in the joint expression of these and other death markers has made it difficult to understand the set of mechanisms influenced beyond the concentration effect of reactive oxygen species to stimulate cell death. Here, the plasma membrane permeability and integrity, phosphatidylserine externalisation and mitochondrial membrane potential were jointly evaluated as death markers in human spermatozoa stimulated with H₂ O₂ . The results showed a profound and sustained effect of dissipation in the mitochondrial membrane potential and an increased phosphatidylserine externalisation in human spermatozoa exposed to 3 mmol^-1 of H₂ O₂ at 30 min. This was followed by an increased membrane permeability after 45 min. The last observed event was the loss of cell membrane integrity at 60 min. In conclusion, mitochondria are rapidly affected in human spermatozoa exposed to reactive oxygen species, with the barely detectable mitochondrial membrane potential coexisting with the high phosphatidylserine externalisation in cells with normal membrane permeability.

Effect of supplementation of valine to chicken extender on sperm cryoresistance and post-thaw fertilization capacity

Recent reports showed a positive correlation between frozen-thawed rooster sperm DNA integrity and the concentrations of valine in seminal plasma. The present study evaluated the effect of supplementing valine to semen extender for freezing sperm of 2 endangered local Spanish chicken breeds with different sperm cryoresistance: Red Villafranquina (VF) showing low sperm DNA integrity after cryopreservation and Quail Castellana that shows higher DNA integrity. One pool of semen per breed was obtained twice a week for 10 wk (n = 40, 20 per breed). Each pool was divided into 2 fractions. One of these fractions was frozen in presence of valine as additive in the extender (concentration 10 mmol), whereas the other was used as control. The evaluation of the samples before and after freezing-thawing included motility (CASA-Mot system), viability (propidium iodide and SYBR-14), DNA integrity (terminal deoxynucleotidyl transferase dUTP nick end labeling), and fertility rate (percentage of eggs with blastoderm development after artificial insemination). Supplementation of valine increased several motility variables of fresh semen. In VF breed, valine increased percentage of progressive motile sperm (P = 0.025), curvilinear velocity (P = 0.033), straight-line velocity (P = 0.040), and average path velocity (P = 0.033), whereas progressive motile sperm (P = 0.019), curvilinear velocity (P = 0.006), straight-line velocity (P = 0.003) and average path velocity (P = 0.004) were improved in the Quail Castellana breed. Valine addition increased the DNA integrity of cryopreserved semen (decreased post-thaw DNA fragmentation) in both breeds, with a significant effect (P = 0.002) in VF (36.3% VF-control vs 31%VF-valine). As expected, Quail Castellana cryopreserved sperm control showed higher fertility rate (34.4% ± 12.1) than VF cryopreserved sperm control (16.1% + 6.2). Supplementing valine to the freezing extender doubled (P = 0.026) the fertility rate of VF (32.6% ± 12.2) compared with the control (16.1% + 6.2). In conclusion, supplementation of valine to chicken freezing extenders shows a positive effect on DNA fragmentation and fertilizing ability of frozen-thawed sperm, with a better response in a breed considered as the lowest freezer in our conservatory.

The association of seminal oxidation reduction potential with sperm parameters in patients with unexplained and male factor ınfertility

Purpose:

Understanding the effects of high oxidation reduction potential (ORP) levels on sperm parameters will help to identify patients with unexplained and male factor infertility who may have seminal oxidative stress and determine if ORP testing is needed. This study aimed to evaluate the association between seminal ORP and conventional sperm parameters.

Materials and Methods:

A total of 58 patients who provided a semen sample for simultaneous evaluation of sperm parameters and ORP between January and September 2019 were enrolled in this retrospective study. To identify normal and high ORP levels, a static ORP (sORP) cut-off value of 1.36mV/10⁶sperm/mL was used. Sperm parameters were compared between infertile men with normal sORP (control group, n=23) and high sORP values (study group, n=35).

Results:

Men with sORP values >1.36mV/10⁶sperm/mL had significantly lower total sperm count (TSC) (p <0.001), sperm concentration (p <0.001) and total motile sperm count (TMSC) (p <0.001). In addition, progressive motility (p=0.04) and fast forward progressive motility (p <0.001) were significantly lower in the study group. A negative correlation was found between sORP and TSC (r=-0.820, p <0.001), sperm concentration (r=-0.822, p <0.001), TMSC (r=-0.808, p <0.001) and progressive motility (r=-0.378, p=0.004). Non-progressive motility positively correlated with sORP (r=0.344, p=0.010).

Conclusions:

This study has shown that TSC, sperm concentration, progressive motility and TMSC are associated with seminal oxidative stress, indicated by a sORP cut-off of 1.36mV/10⁶sperm/mL. Presence of oligozoospermia, reduced progressive motilty or low TMSC in sperm analysis should raise the suspicion of oxidative stress and warrants seminal ROS testing.

The semen microbiome and its impact on sperm function and male fertility: A systematic review and meta-analysis

BACKGROUND

Male factor is attributable in up to 50% of cases of infertility. In vitro studies demonstrate that bacteria can negatively impact sperm function. The use of next-generation sequencing techniques has provided a better understanding of the human microbiome, and dysbiosis has been reported to impact health. Evidence regarding the impact of the semen microbiome on sperm function and fertility remains conflicting.

MATERIALS AND METHODS

A systematic search was conducted in accordance with the Preferred Reporting Items for Reviews and Meta-analysis (PRISMA) statement. The databases MEDLINE, OVID and PubMed were searched to identify English language studies related to the identification of bacteria in the semen of infertile and fertile men, between 1992 and 2019. Fifty-five observational studies were included, with 51 299 subjects. We included studies identifying bacteria using next-generation sequencing, culture or polymerase chain reaction.

RESULTS

The semen microbiome was rich and diverse in both fertile and infertile men. Three NGS studies reported clustering of the seminal microbiome with a predominant species. Lactobacillus and Prevotella were dominant in respective clusters. Lactobacillus was associated with improvements in semen parameters. Prevotella appeared to exert a negative effect on sperm quality. Bacteriospermia negatively impacted sperm concentration and progressive motility, and DNA fragmentation index (DFI; MD: 3.518, 95% CI: 0.907 to 6.129, P = .008). There was an increased prevalence of ureaplasma urealyticum in infertile men (OR: 2.25, 95% CI: 1.47-3.46). Ureaplasma urealyticum negatively impacted concentration and morphology. There was no difference in the prevalence of chlamydia trachomatis between fertile and infertile men and no significant impact on semen parameters. Enterococcus faecalis negatively impacted total motility, and Mycoplasma hominis negatively impacted concentration, PM and morphology.

DISCUSSION AND CONCLUSIONS

Ureaplasma urealyticum, Enterococcus faecalis, Mycoplasma hominis and Prevotella negatively impact semen parameters, whereas Lactobacillus appears to protect sperm quality. These findings may facilitate the development of novel therapies (eg probiotics), although the evidence regarding the impact of the seminal microbiome on fertility is inconclusive and further studies are needed to investigate this association.

An update on the techniques used to measure oxidative stress in seminal plasma

Reactive oxygen species (ROS) are produced in significant amounts by spermatozoa and leucocytes. They are necessary to carry out various physiological functions such as sperm capacitation, hyperactivation, acrosome reaction, sperm-zona binding and cellular signalling pathways. Oxidative stress (OS) results when the ROS levels overwhelm the available antioxidant reserve. A number of direct and indirect tests have been developed to assess oxidative stress. In this manuscript, we discuss these common direct and indirect tests as well as their advantages and disadvantages. Tests measuring sperm dysfunction secondary to oxidative stress such as lipid peroxidation, DNA fragmentation and protein alterations are also described.