Semen leukocytes and oxidative-dependent DNA damage of spermatozoa in male partners of subfertile couples with no symptoms of genital tract infection

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.

Effect of leukocytes on semen quality in men from primary and secondary infertile couples: A cross-sectional study

Background and Aims

Leukocytospermia (LCS) is a known cause of male infertility. However, the relationship between seminal leukocytes and semen quality among infertile couples remains controversial. This study aims to investigate the association between semen quality and LCS in male partners of infertile couples.

Methods

Semen samples were collected from 512 men who asked for a fertility evaluation in a reproductive center in China. Seminal leukocytes were counted following peroxidase staining with benzidine. Other semen parameters were compared in subfertile men with and without LCS.

Results

Poor semen quality (e.g., low semen volume, sperm concentration, and sperm progressive/total motility) was observed among men with LCS compared to those without LCS. Men with LCS had a higher risk of low sperm progressive motility (OR = 0.99, 95% CI = 0.98-0.99, p = 0.02) and total motility (OR = 0.99, 95% CI = 0.98-0.99, p = 0.02), even after adjustment for potential confounders (both OR = 0.99, 95% CI = 0.98-0.99, p = 0.03). Lower sperm viability was observed in LCS from male partners of secondary couples, while no significant difference in semen parameters was found between men with and without LCS in male partners of primary infertile couples. Low sperm motility and viability were associated with LCS in men from secondary infertile couples after adjusting for confounders (OR = 0.97, 95% CI = 0.95-0.99, p = 0.04; OR = 0.94, 95% CI = 0.89-0.99, p = 0.04, respectively).

Conclusions

Our findings indicate that a higher risk of abnormal semen parameters was correlated with an increased number of leukocytes in men from secondary infertile couples.

Cell-type-specific determination of reactive oxygen species by flow cytometry

BACKGROUND

Seminal leukocyte-generated reactive oxygen species may have a significant impact on sperm intracellular reactive oxygen species levels, therefore contributing to oxidative damage and consequent functional impairment of spermatozoa. This relationship may be utilized for male urogenital inflammation-driven oxidative stress diagnostics.

OBJECTIVE

To obtain seminal cell-specific, reactive oxygen species-related fluorescence intensity cut-off values to differentiate leukocytospermic samples displaying reactive oxygen species overproduction (oxidative burst) from normozoospermic seminal samples.

MATERIAL AND METHODS

Ejaculates gained by masturbation were obtained from patients in the framework of andrology consultations. The results published in this paper were generated from samples for which the attending physician requested spermatograms and seminal reactive oxygen species laboratory tests. Routine seminal analyses were performed according to World Health Organization guidelines. Samples were divided into normozoospermic "non-inflamed," and leukocytospermic groups. The semen was stained by 2',7'-dichlorodihydrofluorescein diacetate and the reactive oxygen species-related fluorescence signal and the percentage of reactive oxygen species-positive spermatozoa within the living population were quantified by flow cytometry.

RESULTS

Reactive oxygen species-related mean fluorescence intensity was higher in both spermatozoa and leukocytes from leukocytospermic samples than in those from normozoospermic samples. Mean fluorescence intensity in spermatozoa was positively and linearly correlated with mean fluorescence intensity measured in leukocytes in both groups.

DISCUSSION

The capacity of spermatozoa to generate reactive oxygen species is at least three log lower than that of granulocytes. The question is whether the reactive oxygen species-producing machinery of spermatozoa is capable of causing autologous oxidative stress or whether leukocytes are the predominant source of seminal oxidative stress. Based on our observations, the reactive oxygen species production of leukocytes may have a significant impact on the overall reactive oxygen species levels measured in spermatozoa.

CONCLUSION

Reactive oxygen species-overproducing leukocytospermic and normozoospermic seminal samples can reliably be differentiated based on reactive oxygen species mean fluorescence intensity measurement.

Antioxidants in Male Infertility-If We Want to Get This Right We Need to Take the Bull by the Horns: A Pilot Study

Antioxidant therapy should be reserved for infertile patients who actually exhibit signs of oxidative stress (OS). Nevertheless, there is no consensus regarding the measure of the primary endpoint and the assay that should be used. The formation of 8-hydroxy-2'-deoxyguanosine (8-OHdG), an early marker of sperm DNA oxidation (SDO), was analyzed using flow cytometry, in men at a University hospital setup for infertility treatment. Similar to conventional semen parameters, 8-OHdG assay was validated on fresh semen samples to reduce the variability of results. SDO was associated with semen volume, sperm concentration, leucocytes and round cells, but not with age, body mass index, sperm DNA fragmentation (SDF) or OS. Whether the semen samples were normal or subnormal according to the WHO criteria, the expression of 8-OHdG was not different. Receiver operating characteristic curve analysis could discriminate two independent populations. Both SDF and SDO were independently expressed. A high SDF did not reveal a high SDO and vice versa. The thresholds for SDO have been established, but vary with the techniques used. The methodology for SDO needs to be further validated and optimized on a larger clinically defined patient population before the outcome measure is fit to monitor antioxidant therapy in male infertility.

Oxidative Stress Markers and Sperm DNA Fragmentation in Men Recovered from COVID-19

SARS-CoV-2 negatively affects semen characteristics, impairs various biochemical processes in seminal fluid and within spermatogenic cells ultimately leading to male fertility decline. However, the distinct mechanisms, in particular, the role of oxidative stress on the consequences of coronavirus infection, have not been well investigated, which is the purpose of the present study. The standard semen parameters, its pro- and antioxidant system state, as well as the level of sperm DNA fragmentation, were assessed in 17 semen samples of men five months after the coronavirus infection and in 22 age-matched control patients. We determined that the DNA fragmentation rate negatively correlated with the period after coronavirus recovery, as well as seminal fluid superoxide dismutase activity and uric acid level. It was demonstrated that COVID-19 is not always associated with increased DNA fragmentation, allowing them to be considered as two independent factors. Thus, the most significant changes were noted in the samples of men after COVID-19 and abnormal TUNEL results: increased round cell number, decreased seminal fluid's nitrotyrosine level, and total antioxidant capacity and Zn, as well as an increased 8-hydroxy-2'-deoxyguanosine level within spermatozoa. The data obtained indicate that increased DNA fragmentation and diminished semen quality in men can be the result of an imbalance in semen pro- and antioxidant components after COVID-19.

Oxidative stress and DNA damage status in couples undergoing in vitro fertilization treatment

This study examined the status of oxidative stress in 599 couples undertaking in vitro fertilization (IVF) treatment and its association with reproductive hormones, smoking, and outcomes. Oxidative stress biomarkers such as malondialdehyde, 8-hydroxy-2-deoxyguanosine, hydrogen peroxide (H₂O₂), catalase (CAT), and total antioxidant capacity (TAC) were determined in follicular fluid and seminal plasma. Tail moment (TM) was used to evaluate DNA damage in the sperm and granulosa cells. Reproductive hormones in serum and cotinine (COT) in urine, follicular fluid, and seminal plasma samples were determined. Separate multivariate linear regression was used to assess associations between levels of each oxidative stress biomarker and each hormone and smoking parameter (modeled as natural log-transformed). The findings indicate that some oxidative stress and DNA damage biomarkers played a role in disrupting certain reproductive hormones in women and their male partners either by overproducing reactive oxygen species or reducing antioxidant defense capacity. Although women were nonsmokers, COT levels > 50 and 10 µg/L in urine and follicular were observed in 5.7 and 1.7%, respectively. Levels of follicular fluid COT were positively associated with H₂O₂ and TM. We used log-binomial multivariate regression to estimate relative risks for the association between oxidative stress/DNA damage and IVF binary outcomes (fertilization rate > 50%, biochemical pregnancy, clinical pregnancy, and live birth). An increase in the CAT levels of follicular fluid was associated with a 48 and 41% decrease in the risk of poor fertilization rate (≤50%) and unsuccessful live birth, respectively. After the models were adjusted for hormonal factors, the associations remained the same, except that the elevated TAC in follicular fluid became significantly associated with a decrease of 42% in the risk of poor fertilization rate (≤50%). The higher antioxidant activity (CAT and TAC) in follicular fluid might positively impact specific IVF outcomes.

Fatty Acid Oxidation and Pro-Resolving Lipid Mediators Are Related to Male Infertility

Specialized pro-resolving lipid mediators regulate the resolution of acute inflammation. They are formed by enzymatic oxygenation of polyunsaturated fatty acids and are divided into families including lipoxins, resolvins, protectins, and maresins. Resolvin D1 (RvD1), produced by docosahexaenoic acid, exerts anti-inflammatory and pro-resolving activities. This research aimed to investigate the implication of seminal RvD1 in human infertility. Infertile patients (n° 67) were grouped based on pathological reproductive conditions as idiopathic infertility, varicocele, and leukocytospermia; the fourth group was composed of fertile men (n° 18). Sperm characteristics were evaluated by light microscopy (WHO guidelines) and by transmission electron microscopy (TEM). The seminal levels of RvD1 and F2-isoprostane (F2-IsoPs) were dosed. In twenty men (6 fertile men, 8 with varicocele, 6 with leukocytospermia) seminal phospholipase A2, iron, cholesterol, transferrin, estradiol, ferritin, testosterone, and sperm membrane fatty acids were detected. The results indicated that: (i) RvD1 amount was positively correlated with F2-IsoPs and reduced sperm quality; (ii) RvD1 levels were significantly higher in patients with leukocytospermia, varicocele, and idiopathic infertility compared to fertile men; (iii) RvD1 increased along with other markers of oxidative stress and inflammation as fatty acids content and clinical biomarkers. This study suggests a panel of inflammatory markers and lipid mediators for a diagnosis of inflammatory status and a subsequent appropriate therapeutic approach.

Sexually transmitted infections and semen quality from subfertile men with and without leukocytospermia

BACKGROUND

The role of sexually transmitted infections (STIs) in semen parameters and male infertility is still a controversial area. Previous studies have found bacterial infection in a minority of infertile leukocytospermic males. This study aims to investigate the prevalence of STIs in semen from subfertile men with leukocytospermia (LCS) and without leukocytospermia (non-LCS) and their associations with sperm quality.

METHODS

Semen samples were collected from 195 men who asked for a fertility evaluation. Infection with the above 6 pathogens was assessed in each sample. Sperm quality was compared in subfertile men with and without LCS.

RESULTS

The LCS group had significantly decreased semen volume, sperm concentration, progressive motility, total motility and normal morphology. The infection rates of Ureaplasma urealyticum (Uuu), Ureaplasma parvum (Uup), Mycoplasma hominis (MH), Mycoplasma genitalium (MG), Chlamydia trachomatis (CT), herpes simplex virus-2 (HSV-2) and Neisseria gonorrhoeae (NG) were 8.7 %, 21.0 %, 8.2 %, 2.1 %, 3.6 %, 1.0 and 0 %, respectively. The STI detection rates of patients with LCS were higher than those of the non-LCS group (52.3 % vs. 39.3 %), although there was no statistically significant difference between the two groups (P = 0.07). All semen parameters were not significantly different between LCS with STIs and without STIs, except the semen volume in the MG-infected patients with LCS was significantly lower than that in the noninfected group.

CONCLUSIONS

LCS was associated with a reduction in semen quality, but was not associated with STIs.

Can leukocytospermia predict prostate cancer via its effects on mitochondrial DNA?

Leukocytospermia was previously reported to affect sperm quality by the production of reactive oxygen species (ROS) leading to oxidative stress (OS). In turn, OS decreases sperm functional integrity, increases sperm DNA damage and ultimately alters fertility status. To elucidate the impact of leukocytospermia on sperm nuclear DNA integrity and mitochondrial DNA (mtDNA) structure, we conducted a study including 67 samples from infertile patients with low level of leucocytes (Group 1: n = 20) and with leukocytospermia (Group 2: n = 47). In addition to standard sperm parameters' assessment, we measured the levels of inflammation biomarkers [interleukin-6 (IL-6) and interleukin-8 (IL-8)] and evaluated the oxidative status [malondialdehyde (MDA) and enzymatic and non-enzymatic antioxidants]. In addition, we evaluated the level of sperm nuclear DNA fragmentation and analysed mitochondrial DNA (mtDNA) of sperm cells by sequencing of 5 genes [cytochrome oxidase I (COXI), cytochrome oxidase II (COXII), cytochrome oxidase III (COXIII), adenosine triphosphate synthase 6 (ATPase 6) and adenosine triphosphate synthase 8 (ATPase 8)]. As expected, patients with leukocytospermia had significantly higher MDA levels (32.56 ± 24.30 nmole/ml) than patients without leukocytospermia (17.59 ± 9.60 nmole/ml) (p < .018). Also, sperm DNA fragmentation index (DFI) was significantly higher in Group 2 (33.05 ± 18.14%) as compared to Group 1 (14.19 ± 9.50%) (p < .001). The sequencing of mtDNA revealed a high number of substitutions in Group 2 (n = 102) compared to Group 1 (n = 5). These substitutions were observed mainly in COXI. Among COXI substitutions found in Group 2, twelve changes were previously described in patients with prostate cancer and six of them were shown associated with this pathology. These findings suggest that leukocytospermia may predispose to the manifestation of prostate cancer through modification of mitochondrial DNA and this may be promoted by OS.

Pathophysiology of Mitochondrial Dysfunction in Human Spermatozoa: Focus on Energetic Metabolism, Oxidative Stress and Apoptosis

The dogma of mitochondria as the major source of energy in supporting sperm motility should be critically reconsidered in the light of several experimental data pointing to a major role of glycolysis in mammalian spermatozoa. In this light, the reported positive correlation between the mitochondrial membrane potential (ΔΨm) and motility of ejaculated spermatozoa cannot be explained convincingly by an impaired mitochondrial ATP generation only. Evidence has been produced suggesting that, in human sperm, dysfunctional mitochondria represent the main site of generation of reactive oxygen species (ROS). Furthermore, in these organelles, a complex bidirectional relationship could exist between ROS generation and apoptosis-like events that synergize with oxidative stress in impairing sperm biological integrity and functions. Despite the activity of enzymatic and non-enzymatic antioxidant factors, human spermatozoa are particularly vulnerable to oxidative stress, which plays a major role in male factor infertility. The purpose of this article is to provide an overview of metabolic, oxidative and apoptosis-like inter-linkages of mitochondrial dysfunction and their reflections on human sperm biology.

In vitro ameliorative effects of ellagic acid on vitality, motility and DNA quality in human spermatozoa

Oxidative stress (OS) plays a significant role in the etiology of male infertility, resulting in the impairment of male reproduction. This condition, characterized by an imbalance in the levels of oxidizing and antioxidant species in the seminal fluid, has a harmful impact on sperm functions and DNA integrity. The present study aimed to evaluate the anti-genotoxic action of ellagic acid, a polyphenolic molecule of natural origin having a powerful antigenotoxic, anti-inflammatory and antiproliferative role. An OS condition was induced in vitro by incubating normozoospermic human semen samples in benzene for 45, 60 and 90 min. DNA integrity was evaluated by terminal deoxynucleotidyl transferase dUTP nick end labeling assay, RAPD-PCR was performed to calculate the genome template stability, while the percentage of intracellular reactive oxygen species (ROS) was assessed by the 2', 7'-dichlorofluorescein assay. Our results showed that ellagic acid has a consistent protective effect on DNA integrity, as well as on sperm vitality and motility, by counteracting generation of intracellular ROS. The results of this study suggest ellagic acid as a suitable molecule to protect sperm DNA from oxidative stress, with a potentially significant translational impact on the management of the male infertility.

Reactive Oxygen Species Secreted by Leukocytes in Semen Induce Self-Expression of Interleukin-6 and Affect Sperm Quality

Reproductive tract inflammation is considered an important cause of male infertility. Increased leukocytes in semen can produce many reactive oxygen species (ROS), which affect sperm function. The aim of this study is to identify the main source of ROS in seminal plasma and to assess the effect of ROS on leukocytes. Semen samples (n = 20) with leukocyte concentration >1 × 10⁶ were collected from a male infertility clinic. This study mainly compares the sperm function parameters of the normal group and the semen white blood cell group >1 × 10⁶. The results identified that ROS in semen was closely related to sperm function parameters, and CD45⁺ leucocytes were the main source of ROS. Compared with the control group, the concentration of IL-2, IL-4, IL-6, IFN-γ, and TNF-α was higher in the experimental group. Leukocytes in semen may regulate the secretion of ROS through the mammalian target of rapamycin (mTOR) pathway. A considerable amount of ROS can upregulate the expression of IL-6 in leukocytes via the nuclear factor kappa-B (NF-kB) pathway.

Laboratory and clinical management of leukocytospermia and hematospermia: a review

Leukocytospermia and hematospermia are defined as the presence of abnormally high white blood cell and red blood cell concentration in the semen, respectively. Numerous etiologies and various implications on fertility have been identified. In a small proportion of men, the presence of white blood cells or red blood cells can adversely affect sperm quality by the production of reactive oxygen species. Several methods have been used to assess the presence of white blood cells and red blood cells in samples, such as identification of round cells, immunohistochemical staining using monoclonal antibodies, the Endtz test, the peroxidase test, and flow cytometry or microscopy. In addition, techniques have been identified to separate sperm samples from white blood cells and red blood cells for cryopreservation to improve outcomes in assisted reproductive technology. In this review, laboratory and clinical management of leukocytospermia and hematospermia are discussed. Currently available diagnostic methods and treatment options are outlined, and available optimal cryopreservation techniques for samples with white blood cells or red blood cells are summarized.

Sperm Antioxidant Biomarkers and Their Correlation with Clinical Condition and Lifestyle with Regard to Male Reproductive Potential

Measurement of sperm oxidative-antioxidant indicators is widely used in the assessment and detection of biochemical causes of male infertility The main purpose of this study was to identify biomarkers that assist in diagnostics and monitoring of male reproductive potential. We performed the assessment of oxidative-antioxidant malondialdehyde (MDA), glutathione (GSH), and total redox antioxidant potential (TRAP) indicators in seminal plasma, seminogram, clinical condition, and lifestyle of people with reproductive problems. The combined assessment of GSH and TRAP as potential biomarkers of male infertility in semen plasma was characterized by the highest total sensitivity and specificity. Furthermore, we provide evidence that male reproductive potential is significantly correlated with basic sperm parameters, sperm cell membrane integrity, their morphology, lifestyle, eating habits, occupation, and mental health. Our results provide evidence on the importance of oxidative stress and defense against free radicals in diagnosing and monitoring men with infertility that are consistent with previously conducted research. We provide an alternative approach on the possibility of interpreting the combination of the biomarkers that can bring benefits to a multi-threaded approach to the diagnosis and treatment of male infertility.

Effects of percutaneous varicocele repair on testicular volume: results from a 12-month follow-up

Varicocele is a common finding in men. Varicocele correction has been advocated for young patients with testicular hypotrophy, but there is a lack of morphofunctional follow-up data. We assessed whether percutaneous treatment of left varicocele is associated with testicular "catch-up growth" in the following 12 months by retrospectively reviewing data from an electronic database of 10 656 patients followed up in our clinic between 2006 and 2016. We selected all young adults (<35 years) with left varicocele who underwent percutaneous treatment, had a minimum of 12 months' ultrasound imaging follow-up, and had no other conditions affecting testicular volume. One hundred and fourteen men (mean±standard deviation [s.d.] of age: 22.8 ± 5.4 years) met the inclusion and exclusion criteria. Left testicular hypotrophy (LTH), defined as a ≥20% difference between left and right testicular volume at baseline, was observed in 26 (22.8%) men. Participants with LTH (mean±s.d.: 14.5 ± 2.7 ml) had lower baseline testicular volume compared to those without LTH (mean±s.d.: 15.7 ± 3.8 ml; P = 0.032). Repeated measures mixed models showed a significant interaction between LTH and time posttreatment when correcting for baseline left testicular volume (β = 0.114, 95% confidence interval [CI]: 0.018-0.210, P = 0.020), resulting in a catch-up growth of up to 1.37 ml per year (95% CI: 0.221-2.516). Age at intervention was also associated with reduced testicular volume (-0.072 ml per year, 95% CI: -0.135--0.009; P = 0.024). Percutaneous treatment of left varicocele in young adults with LTH can result in catch-up growth over 1 year of follow-up. The reproductive and psychological implications of these findings need to be confirmed in longer and larger prospective studies.

The Female Response to Seminal Fluid

Seminal fluid is often assumed to have just one function in mammalian reproduction, delivering sperm to fertilize oocytes. But seminal fluid also transmits signaling agents that interact with female reproductive tissues to facilitate conception and .pregnancy. Upon seminal fluid contact, female tissues initiate a controlled inflammatory response that affects several aspects of reproductive function to ultimately maximize the chances of a male producing healthy offspring. This effect is best characterized in mice, where the female response involves several steps. Initially, seminal fluid factors cause leukocytes to infiltrate the female reproductive tract, and to selectively target and eliminate excess sperm. Other signals stimulate ovulation, induce an altered transcriptional program in female tract tissues that modulates embryo developmental programming, and initiate immune adaptations to promote receptivity to implantation and placental development. A key result is expansion of the pool of regulatory T cells that assist implantation by suppressing inflammation, mediating tolerance to male transplantation antigens, and promoting uterine vascular adaptation and placental development. Principal signaling agents in seminal fluid include prostaglandins and transforming growth factor-β. The balance of male signals affects the nature of the female response, providing a mechanism of ‟cryptic female choiceˮ that influences female reproductive investment. Male-female seminal fluid signaling is evident in all mammalian species investigated including human, and effects of seminal fluid in invertebrates indicate evolutionarily conserved mechanisms. Understanding the female response to seminal fluid will shed new light on infertility and pregnancy disorders and is critical to defining how events at conception influence offspring health.

Mediation of the relationship between phthalate exposure and semen quality by oxidative stress among 1034 reproductive-aged Chinese men

BACKGROUND

Emerging evidence from animals indicates that oxidative stress plays a crucial role in the effects of phthalate exposure on male reproductive dysfunctions, which has never been thoroughly explored in humans.

OBJECTIVE

To explore the potential mediating role of oxidative stress in the association of phthalate exposure with semen quality among 1034 Chinese men.

METHOD

Repeated urine samples gathered from the male partners of sub-fertile couples were analyzed for 3 oxidative stress markers [8-hydroxy-2-deoxyguanosine (8-OHdG), 8-iso-prostaglandin F_2α (8-isoPGF_2α) and 4-hydroxy-2-nonenal-mercapturic acid (HNE-MA)], using a liquid chromatography-tandem mass spectrometry. Multivariate regression models were constructed to evaluate the associations of urinary oxidative stress markers with urinary phthalate metabolites and semen quality. We also explored the potential mediation effects by oxidative stress markers.

RESULTS

Significantly positive dose-dependent relationships were observed between each individual phthalate metabolite and all analyzed oxidative stress markers (all p for trend<0.05), except for monoethyl phthalate (MEP) in relation to HNE-MA. Additionally, significantly or suggestively inverse dose-dependent relationships were exhibited between urinary 8-isoPGF_2α and sperm concentration (p for trend = 0.05), and between urinary 8-OHdG and percent of normal sperm morphology (p for trend = 0.01). Mediation analysis showed that urinary 8-isoPGF_2α suggestively mediated 12% of the inverse association between monobutyl phthalate (MBP) and sperm concentration, and that urinary 8-OHdG suggestively mediated 32% of the inverse association of MEP with percent of normal sperm morphology (both p < 0.10).

CONCLUSIONS

Although further investigations are required, our results suggest that oxidative stress may play a mediating role in the effects of phthalate exposure on impaired semen quality.

The association of seminal leucocytes, interleukin-6 and interleukin-8 with sperm DNA fragmentation: A prospective study

The effect of seminal leucocytes on sperm DNA integrity has been discussed controversially in literatures. Moreover, the studies investigating the in vivo effect of pro-inflammatory cytokines interleukin-6 and interleukin-8 on sperm DNA fragmentation are scarce and inconsistent. The association of standard sperm parameters with sperm DNA fragmentation is also a matter of ongoing discussion. Hence, the aims of this study were, first, to evaluate the effect of seminal leucocytes, interleukin-6 and interleukin-8 on sperm DNA integrity and, second, to examine whether standard semen parameters are associated with sperm DNA fragmentation. Seminal leucocytes, interleukin-6, interleukin-8 and standard semen parameters, including total sperm number, sperm concentration, progressive motility, nonprogressive motility, immotility and normal morphology, were determined in 134 consecutive men. The concentrations of seminal leucocytes, interleukin-6 and interleukin-8, did not correlate with sperm DNA fragmentation. In contrast, total sperm number, sperm concentration, progressive motility, nonprogressive motility and normal morphology exhibited significant inverse correlations with sperm DNA fragmentation. Immotile spermatozoa were directly correlated with sperm DNA fragmentation. In conclusion, seminal leucocytes, interleukin-6 and interleukin-8, are not associated with sperm DNA fragmentation. Poor standard semen parameters are significantly related to the high levels of sperm DNA fragmentation.

Interventions to Prevent Sperm DNA Damage Effects on Reproduction

Excessive oxidation and antioxidant imbalance resulting from several conditions may cause sperm DNA damage, which, in turn, affect male fertility, both natural and assisted. Sperm DNA damage transferred to the embryo might also affect the health of offspring. Several conditions associated with excessive oxidative stress are modifiable by the use of specific treatments, lifestyle changes, and averting exposure to environmental/occupational toxicants. Here, we discuss the strategies to reduce sperm DNA damage with a focus on clinical and surgical interventions.

Relationship between leukocytospermia, reproductive potential after assisted reproductive technology, and sperm parameters: a systematic review and meta-analysis of case-control studies

BACKGROUND

The association of leukocytospermia with male fertility is still under debate.

OBJECTIVE

To evaluate the impact of leukocytospermia (≥1 × 10⁶  white blood cells/mL of semen, according to the World Health Organization) in men attending a fertility clinic for couple subfertility, on fertility outcomes after assisted reproductive technology (ART) and on semen quality.

MATERIALS AND METHODS

A systematic review with meta-analysis of case-control studies reporting mean ± standard deviation for values of different seminal parameters (sperm concentration, progressive motility, sperm morphology, sperm DNA fragmentation, semen volume, and Ph) and fertilization rate (FR), or the odds ratio (OR) for clinical pregnancy rate (PR) per cycle after ART in leukocytospermic and non-leukocytospermic patients was performed. A literature search was carried out in MEDLINE and SCOPUS for English-language studies published till June 2018.

RESULTS

Twenty-eight case-controlled retrospective studies met the inclusion criteria, comparing fertility outcomes after ART or semen parameters in men with or without leukocytospermia. FR and PR after ART were not significantly different in the two groups. Leukocytospermic samples showed a lower sperm concentration (pooled SMD = -0.14; 95% CI: -0.28, -0.01, I²  = 71%, p_{for heterogeneity}  < 0.00001) and a lower progressive motility (pooled SMD = -0.18; 95% CI: -0.29, -0.06; I²  = 59%, p_{for heterogeneity}  < 0.0001). However, the significant differences disappeared, along with the large inter-study heterogeneity, when analyses were restricted to studies clearly reporting the inclusion of men without clinical evidence of seminal tract infection.

DISCUSSION AND CONCLUSION

Leukocytospermia in men seeking consultation for couple subfertility is not associated with a reduced fertility after ART and with altered semen quality in populations asymptomatic for genital tract infection. Therefore, the current clinical criteria for definition of leukocytospermia should be re-assessed in subfertile couples attending a fertility clinic.

A Comparison Between Two Assays for Measuring Seminal Oxidative Stress and their Relationship with Sperm DNA Fragmentation and Semen Parameters

Oxidative stress (OS) is a significant cause of DNA fragmentation and is associated with poor embryo development and recurrent miscarriage. The aim of this study was to compare two different methods for assessing seminal OS and their ability to predict sperm DNA fragmentation and abnormal semen parameters. Semen samples were collected from 520 men attending for routine diagnostic testing following informed consent. Oxidative stress was assessed using either a chemiluminescence assay to measure reactive oxygen species (ROS) or an electrochemical assay to measure oxidation reduction potential (sORP). Sperm DNA fragmentation (DFI) and sperm with immature chromatin (HDS) were assessed using sperm chromatin structure assay (SCSA). Semen analysis was performed according to WHO 2010 guidelines. Reactive oxygen species sORP and DFI are negatively correlated with sperm motility (p = 0.0012, 0.0002, <0.0001 respectively) and vitality (p < 0.0001, 0.019, <0.0001 respectively). The correlation was stronger for sORP than ROS. Reactive oxygen species (p < 0.0001), sORP (p < 0.0001), DFI (p < 0.0089) and HDS (p < 0.0001) were significantly elevated in samples with abnormal semen parameters, compared to those with normal parameters. Samples with polymorphonuclear leukocytes (PMN) have excessive ROS levels compared to those without (p < 0.0001), but sORP and DFI in this group are not significantly increased. DNA fragmentation was significantly elevated in samples with OS measured by ROS (p = 0.0052) or sORP (p = 0.004). The results demonstrate the multi-dimensional nature of oxidative stress and that neither assay can be used alone in the diagnosis of OS, especially in cases of leukocytospermia.

Recent Studies on DNA Adducts Resulting from Human Exposure to Tobacco Smoke

DNA adducts are believed to play a central role in the induction of cancer in cigarette smokers and are proposed as being potential biomarkers of cancer risk. We have summarized research conducted since 2012 on DNA adduct formation in smokers. A variety of DNA adducts derived from various classes of carcinogens, including aromatic amines, polycyclic aromatic hydrocarbons, tobacco-specific nitrosamines, alkylating agents, aldehydes, volatile carcinogens, as well as oxidative damage have been reported. The results are discussed with particular attention to the analytical methods used in those studies. Mass spectrometry-based methods that have higher selectivity and specificity compared to 32P-postlabeling or immunochemical approaches are preferred. Multiple DNA adducts specific to tobacco constituents have also been characterized for the first time in vitro or detected in vivo since 2012, and descriptions of those adducts are included. We also discuss common issues related to measuring DNA adducts in humans, including the development and validation of analytical methods and prevention of artifact formation.

Accuracy of human sperm DNA oxidation quantification and threshold determination using an 8-OHdG immuno-detection assay

STUDY QUESTION

Can a discriminant threshold be determined for human sperm DNA oxidation?

SUMMARY ANSWER

A discriminant threshold was found with 65.8% of 8-hydroxy-2'-deoxyguanosine (8-OHdG)-positive sperm cells and a mean intensity of fluorescence (MIF) of 552 arbitrary units.

WHAT IS KNOWN ALREADY

Oxidative stress is known to interfere with sperm quality and fertilizing capacity. However, current practice does not include the routine determination of oxidative DNA damage in spermatozoa; optimized consensus protocols are lacking and no thresholds of normality have been established.

STUDY DESIGN, SIZE, DURATION

Intra- and inter-method comparisons between four protocols (I-IV) were conducted to determine the most relevant and efficient means of assessing human sperm 8-OHdG content. Tests of assay repeatability, specificity, sensitivity and stability were performed to validate an optimized methodology for routine diagnostic use.

PARTICIPANTS/MATERIALS, SETTING, METHODS

This prospective study compared three immuno-detection methods including immunocytochemistry, fluorescence microscopy and flow cytometry. Sperm DNA oxidation for 80 patients was determined relative to semen parameters and clinical conditions, using the selected immuno-detection protocol in comparison with a commercial kit. These patients (age 35 ± 1 years: mean ± SEM) presented with normozoospermic (n = 40) or altered parameters (necro- or/and astheno- or/and teratozoospermia or/and leukocytospermia).

MAIN RESULTS AND THE ROLE OF CHANCE

Significant positive Pearson and Spearman correlations were determined for 8-OHdG values and sperm parameters using protocol III. A notable high and positive correlation was revealed for MIF with BMI and leukocyte concentration. Protocol III was the most discriminating method regarding assay repeatability, specificity, sensitivity, stability and reliability for sperm parameter alterations, in particular leukocytospermia according to parametric or non-parametric tests, effect-size determinations and factorial analysis such as principal component analysis and factor discriminant analysis. Of interest is that 39% of the subjects with 'pathological' sperm DNA oxidation values were normozoospermic.

LIMITATIONS, REASONS FOR CAUTION

The oligozoospermic population was not evaluated in this study because insufficient material was available to carry out the comparisons. However, spermatozoa concentration was taken into account in the statistical analysis.

WIDER IMPLICATIONS OF THE FINDINGS

Our study is the first validation of a protocol to determine a discriminant threshold for human sperm DNA oxidation. The protocol's detection accuracy for 8-OHdG human sperm DNA residues, stability over time, and relationship to human sperm quality were demonstrated. The assay should find application in the diagnosis of male factor infertility associated with oxidative stress.

STUDY FUNDING/COMPETING INTEREST(S)

This work was funded by institutional grants from the CNRS, INSERM and Université Clermont Auvergne (to J.R.D.) and by Clermont-Ferrand Hospital-CECOS research funds (to L.J. and F.B.). P.G., A.M., R.J.A. and J.D. are, respectively, CEO, scientific director and scientific advisors of a US-based biotech company (Celloxess, Princeton, NJ, USA) involved in preventative medicine with a focus on the generation of antioxidant oral supplements.

Testicular spermatozoon is superior to ejaculated spermatozoon for intracytoplasmic sperm injection to achieve pregnancy in infertile males with high sperm DNA damage

The purpose of this study was to compare the clinical outcome of testicular spermatozoon versus ejaculated spermatozoon in the treatment of infertile males with high sperm DNA damage, referred as sperm DNA fragmentation index (DFI), that attending intracytoplasmic sperm injection (ICSI) programme in terms of clinical pregnancy, births delivered as the primary and pregnancy loss and embryo fertilisation as the secondary outcome. A total of 102 males fulfilling the inclusion criteria were enrolled in the present study. Of the 102 males, 61 infertile males underwent testicular spermatozoon combined with ICSI while the remaining 41 males applied ejaculated spermatozoa in their first ICSI cycles, and the data of them were collected and analysed. In a 18-month follow-up, testicular spermatozoon achieved higher pregnancy rate and deliver rate than those in ejaculated sperm group (pregnancy rate, 36% vs. 14.6%, p = 0.017; deliver rate, 38.5% vs. 9.8%, p = 0.001). Nevertheless, there were no significant differences in the number of oocytes aspirated and number of embryos transferred between the two groups. Additionally, the fertilisation rate in the testicular sperm study cohort (70.4%) was also similar to that in the ejaculated sperm group (75.0%). Based on the current data, we conclude that testicular spermatozoon is the prior option in the treatment of infertile males with high sperm DFI in ICSI programme. More high-quality studies with larger samples size are needed in the future due to the relative small size and the nonrandomized design of the present study.