Special Issue "Molecular Immunology of the Male Reproductive System"

The immunological aspects of male infertility have gradually become the focus of both basic and clinical research [...].

Corrigendum: Editorial: Spermatogenesis: from stem cells to spermatozoa

[This corrects the article DOI: 10.3389/fendo.2023.1224313.].

Myd88 Signaling Is Involved in the Inflammatory Response in LPS-Induced Mouse Epididymitis and Bone-Marrow-Derived Dendritic Cells

Epididymitis is an epididymal inflammation that may lead to male infertility. Dendritic cells (DCs) and myeloid differentiation primary response gene 88 (Myd88) were associated with epididymitis in rodents. However, the functions of Myd88 on epididymal DCs remain unclear. This study investigated the role of Myd88 in DCs for epididymitis. The Myd88 signaling pathway, phenotypes of DC subsets, and cytokines were investigated in lipopolysaccharide (LPS)-induced epididymitis in mice. CRISPR-Cas9 was used to knockout Myd88 in bone-marrow-derived dendritic cells (BMDCs) and immortalized mouse epididymal (DC2) cell line. In the vivo experiments, levels of the proinflammatory cytokines IL-1α, IL-6, IL-17A, TNF-α, IL-1β, MCP-1, and GM-CSF, mRNA for MyD88 related genes, and the percentages of monocyte-derived DCs (Mo-DCs) were significantly elevated in mice with epididymitis. In the vitro experiments, LPS significantly promoted the apoptosis of BMDCs. In addition, the concentration of inflammatory cytokines in BMDCs and DC2s were increased in the LPS group, while decreasing after the knockout of Myd88. These findings indicate that Myd88 on DCs is involved in the inflammation of epididymitis in mice, which may be a potential target for better strategies regarding the treatment of immunological male infertility.

CCL20-CCR6 axis directs sperm-oocyte interaction and its dysregulation correlates/associates with male infertility‡

The interaction of sperm with the oocyte is pivotal during the process of mammalian fertilization. The limited numbers of sperm that reach the fallopian tube as well as anatomic restrictions indicate that human sperm-oocyte encounter is not a matter of chance but a directed process. Chemotaxis is the proposed mechanism for re-orientating sperm toward the source of a chemoattractant and hence to the oocyte. Chemokines represent a superfamily of small (8-11 kDa), cytokine-like proteins that have been shown to mediate chemotaxis and tissue-specific homing of leukocytes through binding to specific chemokine receptors such as CCRs. Here we show that CCR6 is abundantly expressed on human sperms and in human testes. Furthermore, radioligand-binding experiments showed that CCL20 bound human sperm in a specific manner. Conversely, granulosa cells of the oocyte-surrounding cumulus complex as well as human oocytes represent an abundant source of the CCR6-specific ligand CCL20. In human ovaries, CCL20 shows a cycle-dependent expression pattern with peak expression in the preovulatory phase and CCL20 protein induces chemotactic responses of human sperm. Neutralization of CCL20 in ovarian follicular fluid significantly impairs sperm migratory responses. Conversely, analyses in infertile men with inflammatory conditions of the reproductive organs demonstrate a significant increase of CCL20/CCR6 expression in testis and ejaculate. Taken together, findings of the present study suggest that CCR6-CCL20 interaction may represent an important factor in directing sperm-oocyte interaction.

Significance of mast cells in spermatogenesis, implantation, pregnancy, and abortion: Cross talk and molecular mechanisms

Both subsets of MCs including MC_TC (tryptase-positive, chymase-positive) and MC_T (tryptase-positive, chymase-negative) are present in the testis and epididymis. Increased number of MCs, higher levels of MC-released tryptase in testis and seminal plasma of males with fertility problems, and promoting sperm motility in individuals with oligozoospermia after using MC blockers provide evidence that MCs may play a role in male infertility/subfertility disturbances. MC-released tryptase and histamine contribute to the fibrosis and may disrupt spermatogenesis. MCs not only influence the process of spermatogenesis but also have effects on the function of other testis-residing cells. MC-derived histamine may influence the steroidogenesis of Leydig cells by acting through H1R and H2R receptors. Additionally, the interaction between MC-released ATP and P2X receptors expressed on the peritubular cells may induce the production of the pro-inflammatory mediators by peritubular cells. Further investigations showed that MCs may be involved in the pathology of female infertility during implantation, pregnancy, and abortion. In the uterus, MC_T subtype is abundant in myometrium and adjacent basal layer while MC_TC subtype is distributed in all layers. MCs in response to hormones mainly estradiol and progesterone become activated and release a wide range of mediators including histamine, VEGF, proteases, and metalloproteinases (MMPs) that have a role in different stages of pregnancy. An increasing influx of MCs to the cervix during the pregnancy occurs that helps to the physiologic cervical ripening. While MMPs degrade the extracellular matrix (ECM), VEGF modulates neovascularization and histamine influences the embryo implantation. MC-derived histamine may have a positive effect during implantation due to its participation in tissue remodeling. MC proteases including tryptase and chymase activate the precursors of MMP2 and MMP9 to mediate ECM degradation during the physiologic menstrual cycle. There is a line of evidence that MCs have a role in abortion by releasing TNF-α.

Human spermatozoa of male patients with subfertility express the interleukin-6 receptor

Male subfertility has been associated with bacterial infections and chronic inflammation. In this context, several studies investigated cytokine levels in seminal plasma, whereas interleukin-6 (IL-6) appears to be crucial. However, little is known about its receptor, the IL-6R expression on human spermatozoa. Thus, the aim of the present study was to screen spermatozoa for IL-6R expression and to identify its localisation. Semen samples of 137 patients (median age 37.69, SD ± 7.82) with subfertility were analysed. Sperm analysis including determination of IL-6 was performed following the World Health Organization criteria. Also, flow cytometry was performed for sperm IL-6R expression. IL-6R⁺ cells were used for immunofluorescence staining to identify receptor localisation. The results showed positive staining for IL-6R in the midpiece of spermatozoa. Furthermore, a significant correlation between sperm IL-6R expression, seminal plasma IL-6 and total sperm count could be demonstrated, whereas a negative correlation was observed in sperm IL-6R expression and motility. However, no statistical significance could be observed between IL-6R expression, vitality and morphology. Moreover, incubation of spermatozoa with IL-6 led to a slight but significant decrease in motility after 24 hr. These data suggest that IL-6R expression may play a role in impaired sperm function during inflammation.

Male Oxidative Stress Infertility (MOSI): Proposed Terminology and Clinical Practice Guidelines for Management of Idiopathic Male Infertility

Despite advances in the field of male reproductive health, idiopathic male infertility, in which a man has altered semen characteristics without an identifiable cause and there is no female factor infertility, remains a challenging condition to diagnose and manage. Increasing evidence suggests that oxidative stress (OS) plays an independent role in the etiology of male infertility, with 30% to 80% of infertile men having elevated seminal reactive oxygen species levels. OS can negatively affect fertility via a number of pathways, including interference with capacitation and possible damage to sperm membrane and DNA, which may impair the sperm's potential to fertilize an egg and develop into a healthy embryo. Adequate evaluation of male reproductive potential should therefore include an assessment of sperm OS. We propose the term Male Oxidative Stress Infertility, or MOSI, as a novel descriptor for infertile men with abnormal semen characteristics and OS, including many patients who were previously classified as having idiopathic male infertility. Oxidation-reduction potential (ORP) can be a useful clinical biomarker for the classification of MOSI, as it takes into account the levels of both oxidants and reductants (antioxidants). Current treatment protocols for OS, including the use of antioxidants, are not evidence-based and have the potential for complications and increased healthcare-related expenditures. Utilizing an easy, reproducible, and cost-effective test to measure ORP may provide a more targeted, reliable approach for administering antioxidant therapy while minimizing the risk of antioxidant overdose. With the increasing awareness and understanding of MOSI as a distinct male infertility diagnosis, future research endeavors can facilitate the development of evidence-based treatments that target its underlying cause.

[Skin diseases and fertility/hormone disorders]

Male fertility can be impaired by a multitude of factors. In addition to environmental and life style factors, such as stress, noise, smoking and overweight, diverse diseases can also have a negative effect on the ability to father a child and the hormone balance, particularly the testosterone level. In many diseases the currently available data do not go beyond observations of limited fertility. In this article the focus is on diseases in the treatment field of dermatology. Special attention is paid to chronic inflammatory and autoimmune skin diseases. Data from recent years show that the excessive inflammatory reaction that these diseases have in common, most probably also has an influence on fertility and interacts with the testosterone concentration in serum. In addition, the impact of hereditary skin diseases on male fertility is discussed, which can have a direct influence on the ability to father a child due to disruption of the hypothalamus-pituitary-gonad axis.

Methylation Markers for the Identification of Body Fluids and Tissues from Forensic Trace Evidence

The identification of body fluids is an essential tool for clarifying the course of events at a criminal site. The analytical problem is the fact that the biological material has been very often exposed to detrimental exogenous influences. Thereby, the molecular substrates used for the identification of the traces may become degraded. So far, most protocols utilize cell specific proteins or RNAs. Instead of measuring these more sensitive compounds this paper describes the application of the differential DNA-methylation. As a result of two genome wide screenings with the Illumina HumanMethylation BeadChips 27 and 450k we identified 150 candidate loci revealing differential methylation with regard to the body fluids venous blood, menstrual blood, vaginal fluid, saliva and sperm. Among them we selected 9 loci as the most promising markers. For the final determination of the methylation degree we applied the SNuPE-method. Because the degree of methylation might be modified by various endogenous and exogenous factors, we tested each marker with approximately 100 samples of each target fluid in a validation study. The stability of the detection procedure is proved in various simulated forensic surroundings according to standardized conditions. We studied the potential influence of 12 relatively common tumors on the methylation of the 9 markers. For this purpose the target fluids of 34 patients have been analysed. Only the cervix carcinoma might have an remarkable effect because impairing the signal of both vaginal markers. Using the Illumina MiSeq device we tested the potential influence of cis acting sequence variants on the methylation degree of the 9 markers in the specific body fluid DNA of 50 individuals. For 4 marker loci we observed such an influence either by sole SNPs or haplotypes. The identification of each target fluid is possible in arbitrary mixtures with the remaining four body fluids. The sensitivity of the individual body fluid tests is in the same range as for the forensic STR-analysis. It is the first forensic body fluid protocol which considers the exogenic and endogenic parameters potentially interfering with the true results.

[Penile dermatoses]

The diagnostics of penile skin alterations represent a urological and dermatological challenge. The spectrum of differential diagnoses ranges from benign skin alterations with no clinical significance, through infections, vesiculobullous diseases and neoplasms up to acute diseases necessitating emergency interventions. Evidence-based therapy concepts are not available for all these diseases and due to the rarity an interdisciplinary cooperation is expedient and promising.

Influence of reactive oxygen species on human sperm functions and fertilizing capacity including therapeutical approaches

BACKGROUND

Reactive oxygen species (ROS) are an array of molecules including oxygen-centered radicals, which are endowed with one or more unpaired electrons and non-radical oxygen derivatives such as hydrogen peroxide, which behave, to a large extent, like a double-edged sword in human sperm biology. This study aimed to overview the current knowledge of ROS in sperm physiology and pathology, as well as related therapies in spermatozoal dysfunction.

METHODS

We performed this study by searching for keywords from PUBMED, including reactive oxygen species, oxidative stress, sperm function, and antioxidant therapy.

RESULTS AND CONCLUSIONS

Low levels of ROS exert critical function in normal sperm physiology, such as fertilizing ability (acrosome reaction, hyperactivation, capacitation, and chemotaxis) and sperm motility; while increased ROS generation and/or decreased antioxidant capacity leads to the imbalance between oxidation and reduction in living systems, which is called sperm oxidative stress. This condition was widely considered to be a significant contributory factor to sperm DNA damage/apoptosis, lipid peroxidation, and reduced motility, which in turn, increased risk of male factor infertility/subfertility and birth defects. Under the current status quo, numerous subsequent studies have concentrated on antioxidant therapy. Although utility of such a therapeutic strategy significantly improved sperm function and motility in a myriad of experimental and clinical reports, the overall effectiveness still remains controversial mainly due to non-standardized assay to measure the level of ROS and sperm DNA damage, various antioxidant supplementation strategies, and inadequate fertilization and pregnancy data after clinical treatment. Therefore, standardized assessment and evaluation of ROS and total antioxidant capacity in semen should be established to keep ROS in a physiological level and prevent over-treatment of antioxidants toward reductive stress, which should be kept in mind, especially in assisted reproductive procedure. Moreover, the significance of large sample size populations, double-blind randomized, placebo-controlled clinical trials of antioxidant therapies is emphasized in this review to achieve optimal ingredients and dosage of antioxidants for patients with reactive oxygen-induced male fertility/subfertility.

New WHO-reference limits-revolution or storm in a teapot?

Since release of the latest WHO manual with the new lower reference values of semen parameters, a lot of discussion has been raised about their usefulness and appropriateness for assessment of male fertility. As with the previous reference values the new limits do neither allow an andrological diagnosis based on nosological criteria nor clear-cut differentiation between fertility and sub-/infertility. Therefore, considering the fact that fertility is a continuum, the new lower reference limits should not be overestimated. Most probably, more sperm function tests, such as determination of DNA integrity, and-in the future-assessment of biomarkers, such as sperm proteomics will be included into andrological work-up, thus resulting in a more personalized approach of infertility management. On the other hand, the detailed instructions for standard and advanced semen analysis provided in the new manual are very much appreciated and should be adopted by each seriously working laboratory.

[Orchitis and male infertility]

Infections and inflammations of the genital tract are considered the most frequent causes of reduced male fertility, but conclusive epidemiological data are not available. In view of the exposure of germ cells to pathogenic components as well as the cells and mediators involved in the inflammatory processes, irreversible damage to spermatogenesis and corresponding decline of ejaculate quality are to be expected, particularly in cases of chronic orchitis. While the consequences of orchitis and epididymo-orchitis that exhibit clinical symptoms due to systemic or local infections are well known, including testicular atrophy and complete loss of fertility, those cases of inflammatory reactions of the testicles that manifest an asymptomatic or subclinical course, or are not even due to an infection, have received little attention until now. However, systematic histopathological analyses have shown a high prevalence of asymptomatic inflammatory reactions in testicular biopsies from infertile men. The mostly focal lymphocytic infiltrates correlate with the degree of damage to spermatogenesis and corresponding clinical and endocrinological parameters of testicular function. Noninvasive diagnostic techniques are not yet available so that chronic asymptomatic inflammations of the testicles as the primary cause or cofactor of male fertility disorders are underestimated. Except for administration of pathogen-specific antibiotics, treatment recommendations are to a large extent still lacking.

Advances in the management of male infertility

Male infertility can be treated by surgical procedures (e.g., varicocelectomy) or by administration of drugs if causal factors (e.g., seminal tract infections) are detected. In more severe cases, methods of assisted fertilization often have to be applied, but even these have only a limited success rate. Recent studies have demonstrated that disturbances of sperm DNA integrity (determined by the acridine orange test) can explain certain cases of fertilization failure and failure to achieve pregnancy following in vitro fertilisation with intracytoplasmic sperm injection. The evaluation of DNA integrity should be considered when diagnosing male infertility as it has been shown to be an independent factor and can be used as a supplement to standard semen analysis. Analysis of DNA integrity may, therefore, provide further information about altered male fertility and lead to administration of more appropriate therapy.

Embolization of varicocles: pretreatment sperm motility predicts later pregnancy in partners of infertile men

PURPOSE

To identify predictors of future pregnancy in partners of infertile men undergoing embolization of varicoceles.

MATERIALS AND METHODS

This study was conducted within local institutional review board guidelines, and written informed consent was obtained. In 223 clinically infertile men (age range, 18-50 years) with varicoceles and associated oligoteratoasthenospermia, endovascular embolization of the spermatic veins was performed with distal coil embolization and sclerotherapy. Additional anti-inflammatory treatment was initiated if required. Baseline clinical examination, semen specimen, and hormone level findings were compared to follow-up data. Posttreatment pregnancy rate of their healthy female partners was assessed with a standardized questionnaire. Unconditioned logistic regression was used to identify factors among all available clinical and laboratory data predicting treatment success (sired pregnancy during follow-up).

RESULTS

A total of 226 of 228 varicoceles in 223 patients were successfully treated. Resolution of varicoceles at clinical examination and ultrasonography (US) was observed in 206 patients (92.4%). Three-month follow-up semen analysis in these patients showed significant improvement in sperm motility (P < .001) and sperm count (P < .001); however, average values remained in the abnormal range (World Health Organization guidelines). In 173 patients, follow-up data were successfully obtained, with pregnancy reported in 45 (26%). Baseline sperm motility was identified as the only significant pretreatment factor (standardized regression coefficient beta = 3.285, t = 7.560, P = .006) predicting sired pregnancy. Hormone levels, clinical grading of varicoceles, Doppler US findings, and other semen parameters did not reach statistical significance.

CONCLUSION

Sperm motility prior to varicocele treatment in infertile men is an important predictor of later pregnancy.

Relationship between anger and pruritus perception in patients with chronic idiopathic urticaria and psoriasis

BACKGROUND

There is evidence that chronic idiopathic urticaria (CIU) and psoriasis are associated with personality based difficulties in emotional regulation particularly with regard to the feeling of anger. This deficit in emotional awareness could lead to the phenomenon that emotions are rather experienced in bodily symptoms such as pruritus.

AIM

We investigated whether there is a relationship between pruritus as major symptoms in CIU and psoriasis and the experience of negative emotions.

SETTING

Forty-one CIU patients and 44 psoriasis patients treated at Bonn University Hospital and 49 healthy controls were included.

METHOD

Patients and controls were compared on questionnaires measuring alexithymia (TAS-20), emotional distress (SCL-90-R) and anger (STAXI). In skin-disordered patients, separate stepwise regressions with pruritus severity as dependent variable and questionnaires, skin status, duration, sex and age as independent variables were calculated.

RESULTS

CIU and psoriasis patients showed higher alexithymia, emotional distress, depression, anxiety and state anger compared with controls. State anger was the only significant predictor of pruritus severity in CIU explaining 19% of variance. Depression was the only significant predictor of pruritus severity in psoriasis explaining 12% of variance.

CONCLUSIONS

Our findings suggest a relationship between pruritus severity and anger in CIU. Furthermore, our results indicate a relationship between pruritus severity and depression in psoriasis.

Andrology

Andrology is part of dermatology in Germany, as it arose from dermatology as a subspecialty. Accordingly training in andrology is part of the curriculum for specialty certification in dermatology. All dermatologists are required to "have experience in the diagnosis of andrologic disorders and their subsequent treatment". The specialty of andrology deals with male infertility problems including questions regarding fertility prophylaxis, contraception, erectile dysfunction, disturbance in libido, ejaculation and copulation, and primary and secondary hypogonadism, as well as male aging and diseases of the male breast. Evaluation and treatment of the partner may also be necessary. Ejaculate analysis is the most important laboratory tool and each dermatologist must be qualified in its performance.

Flushing and increase of serum tryptase after mechanical irritation of a solitary mastocytoma

Solitary mastocytomas are infiltrates of mast cells in the upper corium, appearing at any side of the body as brownish-reddish plaques in the first months of life. Their course is benign with a spontaneous regression in most cases. A 5-month-old boy presented a 5 x 3 cm sized brownish-yellow plaque on the back of his right hand. His parents reported repeated episodes of swelling and blistering of the skin lesion as well as recurrent systemic flush-reactions. General laboratory parameters were without pathological findings including a normal serum tryptase (5.5 microg/L). A few minutes after rubbing, the lesion became urticarially swollen and the infant developed a general flush reaction accompanied by a bilateral miosis and asthma-like symptoms which disappeared completely after oral administration of 7 drops of dimentinden. Assessment of the serum tryptase two hours after the provocation revealed a more than 5-fold increase (29.3 microg/L) compared to the basic value. We conclude that uncontrolled stroking of mastocytomas should be avoided in patients with a systemic reaction in their history, since this case demonstrates that despite its limited size, mechanical irritation of a solitary mastocytoma may induce strong systemic symptoms as witnessed by transient increase of the serum tryptase, which to our knowledge has not been described in the literature before.

Age-related changes in seminal polymorphonuclear elastase in men with asymptomatic inflammation of the genital tract

AIM

To investigate age-related inflammatory events in the male genital tract.

METHODS

In a total of 4265 randomly collected patients attending the andrological outpatient clinic of the Center for Dermatology and Andrology, University of Giessen, Germany, ejaculate volume, pH-value, sperm concentration, total and progressive sperm motility, concentration of polymorphonuclear (PMN) elastase, number of peroxidase-positive cells and fructose were measured and correlated with patient's age.

RESULTS

While ejaculate volume, motility and fructose all correlated negatively with age, sperm concentration, PMN elastase and the pH-value showed a positive correlation. The prevalence of male genital tract inflammation (as defined by PMN elastase > 250 ng/mL) and its severity increased significantly. PMN elastase did not correlate with sperm motility. Fructose as a marker of seminal vesicle function showed a significant negative relationship with the PMN elastase levels, the number of peroxidase-positive cells and sperm motility.

CONCLUSION

The significant increases of PMN-elastase levels as marker of male genital tract inflammation in older men appear to be indicative of age-related changes in local immunoregulatory mechanisms. Because there is no association of PMN elastase with sperm motility, a direct inhibitory effect of this enzyme can be excluded.