Relationship between nuclear DNA fragmentation, mitochondrial DNA damage and standard sperm parameters in spermatozoa of infertile patients with leukocytospermia

Effects of Reactive Oxygen and Nitrogen Species on Male Fertility

Significance: In recent decades, male fertility has been severely reduced worldwide. The causes underlying this decline are multifactorial, and include, among others, genetic alterations, changes in the microbiome, and the impact of environmental pollutants. Such factors can dysregulate the physiological levels of reactive species of oxygen (ROS) and nitrogen (RNS) in the patient, generating oxidative and nitrosative stress that impairs fertility. Recent Advances: Recent studies have delved into other factors involved in the dysregulation of ROS and RNS levels, such as diet, obesity, persistent infections, environmental pollutants, and gut microbiota, thus leading to new strategies to solve male fertility problems, such as consuming prebiotics to regulate gut flora or treating psychological conditions. Critical Issues: The pathways where ROS or RNS may be involved as modulators are still under investigation. Moreover, the extent to which treatments can rescue male infertility as well as whether they may have side effects remains, in most cases, to be elucidated. For example, it is known that prescription of antioxidants to treat nitrosative stress can alter sperm chromatin condensation, which makes DNA more exposed to ROS and RNS, and may thus affect fertilization and early embryo development. Future Directions: The involvement of extracellular vesicles, which might play a crucial role in cell communication during spermatogenesis and epididymal maturation, and the relevance of other factors such as sperm epigenetic signatures should be envisaged in the future.

Leukocytospermia does not negatively impact outcomes in in vitro fertilization cycles with intracytoplasmic sperm injection and preimplantation genetic testing for aneuploidy: findings from 5435 cycles

PURPOSE

To investigate whether leukocytospermia (defined as the presence of ≥ 1 × 106 white blood cells/mL) affects clinical and embryologic outcomes in in vitro fertilization (IVF) cycles with intracytoplasmic sperm injection (ICSI) and preimplantation genetic testing for aneuploidy (PGT-A).

METHODS

This was a retrospective cohort study including 5425 cycles between January 2012 to December 2021 at a single large university-affiliated fertility clinic. The primary outcome was live birth rate (LBR).

RESULTS

The prevalence of leukocytospermia was 33.9% (n = 1843). Baseline characteristics including female age, BMI, AMH, Day 3 FSH, and male partner's age were similar in cycles with and without leukocytospermia. The LBR after the first euploid embryo transfer was similar in those with and without leukocytospermia (62.3% vs. 63% p = 0.625). Secondary outcomes including clinical pregnancy rate (CPR), sustained implantation rate (SIR), fertilization (2PN) rate, blastulation rate, and aneuploidy rate were also evaluated. The CPR (73.3% vs 74.9%, p = 0.213) and SIR (64.6% vs. 66%, p = 0.305) were similar in both groups. The 2PN rate was also similar in both groups (85.7% vs. 85.8%, p = 0.791), as was the blastulation rate per 2PN (56.7% vs. 57.5%, p = 0.116). The aneuploidy rate was not significantly different between groups (25.7% vs 24.4%, p = 0.053). A generalized estimation equation with logistic regression demonstrated that the presence leukocytospermia did not influence the LBR (adjusted OR 0.878; 95% CI, 0.680-1.138).

CONCLUSION

Leukocytospermia diagnosed just prior to an IVF cycle with PGT-A does not negatively impact clinical or embryologic outcomes.

An Alternative Application of Magnetic-Activated Cell Sorting: CD45 and CD235a Based Purification of Semen and Testicular Tissue Samples

Magnetic activated cell sorting (MACS) is a well-known sperm selection technique, which is able to remove apoptotic spermatozoa from semen samples using the classic annexinV based method. Leukocytes and erythrocytes in semen samples or in testicular tissue processed for in vitro fertilization (IVF) could exert detrimental effects on sperm. In the current study, we rethought the aforementioned technique and used magnetic microbeads conjugated with anti-CD45/CD235a antibodies to eliminate contaminating leukocytes and erythrocytes from leukocytospermic semen samples and testicular tissue samples gained via testicular sperm extraction (TESE). With this technique, a 15.7- and a 30.8-fold reduction could be achieved in the ratio of leukocytes in semen and in the number of erythrocytes in TESE samples, respectively. Our results show that MACS is a method worth to reconsider, with more potential alternative applications. Investigations to find molecules labeling high-quality sperm population and the development of positive selection procedures based on these might be a direction of future research.

Unravelling the epigenetic impact: Oxidative stress and its role in male infertility-associated sperm dysfunction

Male infertility is a multifactorial condition influenced by epigenetic regulation, oxidative stress, and mitochondrial dysfunction. Oxidative stress-induced damage leads to epigenetic modifications, disrupting gene expression crucial for spermatogenesis and fertilization. Paternal exposure to oxidative stress induces transgenerational epigenetic alterations, potentially impacting male fertility in offspring. Mitochondrial dysfunction impairs sperm function, while leukocytospermia exacerbates oxidative stress-related sperm dysfunction. Therefore, this review focuses on understanding these mechanisms as vital for developing preventive strategies, including targeting oxidative stress-induced epigenetic changes and implementing lifestyle modifications to prevent male infertility. This study investigates how oxidative stress affects the epigenome and sperm production, function, and fertilization. Unravelling the molecular pathways provides valuable insights that can advance our scientific understanding. Additionally, these findings have clinical implications and can help to address the significant global health issue of male infertility.

[Infections and male infertility]

BACKGROUND

The role of urogenital infections in male infertility has long been the subject of debate.

METHODS

A bibliographic search limited to English-language literature on human subjects published before 5/2023 resulted in the selection of 189 articles.

RESULTS

Male infertility is often of multifactorial aetiology, and to optimise the prognosis it is important to manage all the factors that can be corrected, including infectious causes, which represent one of the most frequent aetiologies. The infectious agents involved in urogenital infections are most often bacterial or viral, and more rarely parasitic. They can infect the seminal tract, male accessory glands and/or testicles, and usually result in inflammation and increased oxidative stress. These infections reduce male fertility, in particular by altering spermogram parameters and increasing sperm DNA fragmentation. For these reasons, the search for a urogenital infection should be systematic, involving a careful history and clinical examination, ultrasound and systematic bacteriological tests guided by clinical findings. Aetiological treatment may be proposed depending on the picture and the germ involved.

CONCLUSION

This review should help the urologist to establish an accurate diagnosis of the form and extent of the infection, and enable him to define an appropriate therapeutic strategy, tailored to the patient, in order to obtain the best chances of improving male fertility.

Analytical validation of five diagnostic tests for the detection of polymorphonuclear cells in stallion semen

The objectives of this study were to evaluate the ability of five diagnostic tests to detect polymorphonuclear cells (PMNs) in stallion semen, and to determine the concentration of PMNs that affects sperm motility. We hypothesized that all tests have diagnostic value, and even low concentrations of PMNs affect motility. One ejaculate was obtained from six stallions. Aliquots of 50 × 10⁶ purified sperm were incubated, in triplicate, with six concentrations of purified PMNs: 1) no PMNs, 2) 0.25 × 10⁶ PMN/ml, 3) 0.5 × 10⁶ PMN/ml, 4) 2.5 × 10⁶ PMN/ml, 5) 5 × 10⁶ PMN/ml, 6) 10 × 10⁶ PMN/ml. The PMNs were quantified using a hemacytometer, cytology, a leucocyte esterase dipstick test (LEDT), a peroxidase test, and CD13 immunolabeling. Sperm motility was evaluated after 4 h at 38 °C. The number of leucocytes detected with the LEDT differed among treatments (P<0.0001), from negative results in control samples to moderate or large numbers in the samples with the highest PMN concentration. The hemacytometer count and CD13 immunostaining detected differences with the control treatment at the lowest PMN concentration (2.5 × 10⁶ PMN/ml; P<0.001). Sperm motion was lower in samples with ≥5 × 10⁶ PMN/ml (P<0.0001). Thus, a sample was considered leucospermic if it contained ≥5 × 10⁶ PMN/ml. The LEDT had the best sensitivity (100%), followed by cytology (78%), peroxidase test (60%), CD13 immunostaining (56%) and hemacytometer count (47%). The LEDT had the lowest specificity (65%), which was 95% for all other tests. In conclusion, the LEDT was a simple, economic and sensitive stall-side test to screen semen for presence of PMNs. Because of the lower specificity, positive LEDT results should be confirmed with the identification of peroxidase-positive cells or CD13-positive cells.

Relevance of Leukocytospermia and Semen Culture and Its True Place in Diagnosing and Treating Male Infertility

The current WHO 2010 manual for human semen analysis defines leukocytospermia as the presence of peroxidase-positive leukocytes at a concentration >1×106/mL of semen. Granular leukocytes when activated are capable of generating high levels of reactive oxygen species in semen resulting in oxidative stress. Oxidative stress has been correlated with poor sperm quality, increased level of sperm DNA fragmentation and low fertility potential. The presence of leukocytes and pathogens in the semen may be a sign of infection and/or localized inflammatory response in the male genital tract and the accessory glands. Common uro-pathogens including Chlamydia trachomatis, Ureaplasma urealyticum, Neisseria gonorrhoeae, Mycoplasma hominis, and Escherichia coli can cause epididymitis, epididymo-orchitis, or prostatitis. The relationship between leukocytospermia and infection is unclear. Therefore, we describe the pathogens responsible for male genital tract infections and their association with leukocytospermia. The review also examines the diagnostic tests available to identify seminal leukocytes. The role of leukocytospermia in male infertility and its management is also discussed.

Male Infertility and Oxidative Stress: A Focus on the Underlying Mechanisms

Reactive oxygen species (ROS) play a critical role in defining the functional competence of human spermatozoa. When generated in moderate amounts, ROS promote sperm capacitation by facilitating cholesterol efflux from the plasma membrane, enhancing cAMP generation, inducing cytoplasmic alkalinization, increasing intracellular calcium levels, and stimulating the protein phosphorylation events that drive the attainment of a capacitated state. However, when ROS generation is excessive and/or the antioxidant defences of the reproductive system are compromised, a state of oxidative stress may be induced that disrupts the fertilizing capacity of the spermatozoa and the structural integrity of their DNA. This article focusses on the sources of ROS within this system and examines the circumstances under which the adequacy of antioxidant protection might become a limiting factor. Seminal leukocyte contamination can contribute to oxidative stress in the ejaculate while, in the germ line, the dysregulation of electron transport in the sperm mitochondria, elevated NADPH oxidase activity, or the excessive stimulation of amino acid oxidase action are all potential contributors to oxidative stress. A knowledge of the mechanisms responsible for creating such stress within the human ejaculate is essential in order to develop better antioxidant strategies that avoid the unintentional creation of its reductive counterpart.

Sperm Vitality and Necrozoospermia: Diagnosis, Management, and Results of a Global Survey of Clinical Practice

Sperm vitality testing is a basic semen examination that has been described in the World Health Organization (WHO) Laboratory Manual for the Examination and Processing of Human Semen from its primary edition, 40 years ago. Several methods can be used to test sperm vitality, such as the eosin-nigrosin (E-N) stain or the hypoosmotic swelling (HOS) test. In the 6th (2021) edition of the WHO Laboratory Manual, sperm vitality assessment is mainly recommended if the total motility is less than 40%. Hence, a motile spermatozoon is considered alive, however, in certain conditions an immotile spermatozoon can also be alive. Therefore, the differentiation between asthenozoospermia (pathological decrease in sperm motility) and necrozoospermia (pathological decrease in sperm vitality) is important in directing further investigation and management of infertile patients. The causes leading to necrozoospermia are diverse and can either be local or general, testicular or extra-testicular. The andrological management of necrozoospermia depends on its etiology. However, there is no standardized treatment available presently and practice varies among clinicians. In this study, we report the results of a global survey to understand current practices regarding the physician order of sperm vitality tests as well as the management practices for necrozoospermia. Laboratory and clinical scenarios are presented to guide the reader in the management of necrozoospermia with the overall objective of establishing a benchmark ranging from the diagnosis of necrozoospermia by sperm vitality testing to its clinical management.

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.