Impaired Leydig cell function in infertile men: a study of 357 idiopathic infertile men and 318 proven fertile controls

Hexafluoropropylene oxide trimer acid (HFPO-TA) exerts cytotoxic effects on leydig cells via the ER stress/JNK/β-trcp/mcl-1 axis

Hexafluoropropylene oxide trimer acid (HFPO-TA) is an alternative to perfluorooctanoic acid (PFOA) and is widely used in various industries. The effects of HFPO-TA on the male reproductive system and the underlying mechanisms are still not fully understood. In this study, TM3 mouse Leydig cells were used as the main model to evaluate the cytotoxicity of HFPO-TA in vitro. HFPO-TA inhibited the viability and expression of multiple biomarkers of Leydig cells. HFPO-TA also induced Leydig cell apoptosis in a caspase-dependent manner. Moreover, HFPO-TA induced the ubiquitination and degradation of Mcl-1 in a β-TrCP-dependent manner. Further investigations showed that HFPO-TA treatment led to the upregulation of ROS, which activated the ER stress/JNK/β-TrCP axis in Leydig cells. Overall, our study provides novel insights into the cytotoxic effects of HFPO-TA on the male reproductive system.

Loss of PBX1 function in Leydig cells causes testicular dysgenesis and male sterility

Leydig cells are essential components of testicular interstitial tissue and serve as a primary source of androgen in males. A functional deficiency in Leydig cells often causes severe reproductive disorders; however, the transcriptional programs underlying the fate decisions and steroidogenesis of these cells have not been fully defined. In this study, we report that the homeodomain transcription factor PBX1 is a master regulator of Leydig cell differentiation and testosterone production in mice. PBX1 was highly expressed in Leydig cells and peritubular myoid cells in the adult testis. Conditional deletion of Pbx1 in Leydig cells caused spermatogenic defects and complete sterility. Histological examinations revealed that Pbx1 deletion impaired testicular structure and led to disorganization of the seminiferous tubules. Single-cell RNA-seq analysis revealed that loss of Pbx1 function affected the fate decisions of progenitor Leydig cells and altered the transcription of genes associated with testosterone synthesis in the adult testis. Pbx1 directly regulates the transcription of genes that play important roles in steroidogenesis (Prlr, Nr2f2 and Nedd4). Further analysis demonstrated that deletion of Pbx1 leads to a significant decrease in testosterone levels, accompanied by increases in pregnenolone, androstenedione and luteinizing hormone. Collectively, our data revealed that PBX1 is indispensable for maintaining Leydig cell function. These findings provide insights into testicular dysgenesis and the regulation of hormone secretion in Leydig cells.

Are they functional hypogonadal men? Testosterone serum levels unravel male idiopathic infertility subgroups

PURPOSE

To evaluate total testosterone distribution in male idiopathic infertility.

METHODS

A retrospective, real-world case-control clinical study was conducted. Cases consisted of men evaluated for couple infertility, specifically those with alterations in semen parameters and normal gonadotropin levels, and after excluding all known causes of male infertility. Controls were male subjects who underwent semen analysis for screening purposes, without any abnormality detected. The total testosterone distribution was evaluated in cases and controls. Further analyses were performed subgrouping cases according to total testosterone reference threshold suggested by scientific societies (i.e., 3.5 ng/mL).

RESULTS

Cases included 214 idiopathic infertile men (mean age 38.2 ± 6.2 years) and controls 224 subjects with normozoospermia (mean age 33.7 ± 7.5 years). Total testosterone was not-normally distributed in both cases and controls, with positive asymmetric distribution slightly shifted on the left in cases. The rate of subjects with testosterone lower than 3.5 ng/mL was higher in cases (23.8%) than controls (4.5%) (p < 0.001). In cases with testosterone lower than 3.5 ng/mL, a significant direct correlation between testosterone and the percentage of normal morphology sperms was highlighted, also applying multivariate stepwise linear regression analysis (R = 0.430, standard error = 0.3, p = 0.020).

CONCLUSION

Although idiopathic infertile men show by definition altered semen analysis and gonadotropins within reference ranges, testosterone serum levels are widely variable in this population. Approximately a quarter of these patients present some sort of functional hypogonadism. Our data support the need to better classify idiopathic male infertility and total testosterone serum levels could be a supportive parameter in tracing the patient's therapeutic profile.

Enniatin B1 induces damage to Leydig cells via inhibition of the Nrf2/HO-1 and JAK/STAT3 signaling pathways

Enniatin B1 (ENN B1) is a mycotoxin that can be found in various foods. However, whether ENN B1 is hazardous to the reproductive system is still elusive. Leydig cells are testosterone-generating cells that reside in the interstitial compartment between seminiferous tubules. Dysfunction of Leydig cells could result in male infertility. This study aimed to examine the toxicological effects of ENN B1 against TM3 Leydig cells. ENN B1 significantly inhibited cell viability in a dose-dependent manner. ENN B1 treatment also decreased the expression of functional genes in Leydig cells. Moreover, ENN B1 induced Leydig cells apoptosis and oxidative stress. Mechanistically, ENN B1 leads to the upregulation of Bax and downregulation of Bcl-2 in Leydig cells. In addition, ENN B1 inhibited the Nrf2/HO-1 pathway, which is critical for the induction of oxidative stress. Additionally, ENN B1 treatment repressed the JAK/STAT3 signaling pathway in Leydig cells. Rescue experiments showed that activation of STAT3 resulted in alleviation of ENN B1-induced damage in Leydig cells. Collectively, our study demonstrated that ENN B1 induced Leydig cell dysfunction via multiple mechanisms.

Comprehensive evaluation of inactivated SARS-CoV-2 vaccination on sperm parameters and sex hormones

Background

The inactivated severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine has made significant contributions to fighting the epidemic in the past three years. However, the rapid development and application raised concerns about its safety in reproductive health, especially after several studies had observed a decrease in semen parameters following two doses of mRNA SARS-CoV-2 vaccination. Thus, it is necessary to comprehensively evaluate the effect of inactivated SARS-CoV-2 vaccine on male fertility.

Methods

A retrospective cohort study was conducted in the Center for Reproductive Medicine of the Affiliated Hospital of Jining Medical University between July 2021 and March 2023. A total of 409 men with different vaccination status and no history of SARS-CoV-2 infection were included in this study. Their sex hormone levels and semen parameters were evaluated and compared separately.

Results

The levels of FSH and PRL in one-dose vaccinated group were higher than other groups, while there were no significant changes in other sex hormone levels between the control and inactivated SARS-CoV-2 vaccinated groups. Most semen parameters such as volume, sperm concentration, total sperm count, progressive motility and normal forms were similar before and after vaccination with any single dose or combination of doses (all P > 0.05). Nevertheless, the total motility was significantly decreased after receiving the 1 + 2 doses of vaccine compared to before vaccination (46.90 ± 2.40% vs. 58.62 ± 2.51%; P = 0.001). Fortunately, this parameter was still within the normal range.

Conclusion

Our study demonstrated that any single dose or different combined doses of inactivated SARS-CoV-2 vaccination was not detrimental to male fertility. This information could reassure men who want to conceive after vaccination and be incorporated into future fertility recommendations.

Frequency, morbidity and equity - the case for increased research on male fertility

Currently, most men with infertility cannot be given an aetiology, which reflects a lack of knowledge around gamete production and how it is affected by genetics and the environment. A failure to recognize the burden of male infertility and its potential as a biomarker for systemic illness exists. The absence of such knowledge results in patients generally being treated as a uniform group, for whom the strategy is to bypass the causality using medically assisted reproduction (MAR) techniques. In doing so, opportunities to prevent co-morbidity are missed and the burden of MAR is shifted to the woman. To advance understanding of men's reproductive health, longitudinal and multi-national centres for data and sample collection are essential. Such programmes must enable an integrated view of the consequences of genetics, epigenetics and environmental factors on fertility and offspring health. Definition and possible amelioration of the consequences of MAR for conceived children are needed. Inherent in this statement is the necessity to promote fertility restoration and/or use the least invasive MAR strategy available. To achieve this aim, protocols must be rigorously tested and the move towards personalized medicine encouraged. Equally, education of the public, governments and clinicians on the frequency and consequences of infertility is needed. Health options, including male contraceptives, must be expanded, and the opportunities encompassed in such investment understood. The pressing questions related to male reproductive health, spanning the spectrum of andrology are identified in the Expert Recommendation.

The fate of germ cells in cryptorchid testis

Cryptorchidism in males constitutes a notable risk factor for both infertility and testicular cancer. Infertility in adulthood is closely linked to the germ cell status in childhood. Furthermore, the significance of germ cell status is important as more than 95% of all reported testicular malignancies are germ cell tumors. The review aims to elucidate the pathogenesis of germ cells in cryptorchid testes concerning their association with infertility and testicular malignancies. Impaired germ cell numbers are evident in cryptorchid testes even during antenatal and neonatal stages. In cryptorchidism there is a rapid decline in germ cell number within the first year of life, partially attributed to physiologic gonocyte apoptosis. Additionally, germ cells fail to differentiate normally during mini-puberty leading to reduced germ cell proliferation and delayed clearance of gonocytes from the seminiferous epithelium. Absence of germ cells in testicular biopsies occurs already 10 months of age and germ cell deterioration progressively worsens with approximately 50% of persisting cryptorchid testes lacking germ cells during puberty. The deficient germ cell maturation and proliferation leads to later infertility. Elevated temperature in the cryptorchid testes and also hormonal deficiency contribute to this phenomenon. Germ cell neoplasia in situ (GCNIS) originating during fetal development may manifest in rare cases associated with disorders of sexual development, chromosomal abnormalities in boys, specific syndromes, and teratomas that include cryptorchidism. In adults, the presence of GCNIS predominantly represents a new histology pattern before invasive germ cell cancer is demonstrated and is neither congenital nor related to abnormal gonocyte transformation.

Unlocking the mystery associated with infertility and prostate cancer: an update

Male-specific reproductive disorders and cancers have increased intensely in recent years, making them a significant public health problem. Prostate cancer (PC) is the most often diagnosed cancer in men and is one of the leading causes of cancer-related mortality. Both genetic and epigenetic modifications contribute to the development and progression of PC, even though the exact underlying processes causing this disease have yet to be identified. Male infertility is also a complex and poorly understood phenomenon believed to afflict a significant portion of the male population. Chromosomal abnormalities, compromised DNA repair systems, and Y chromosome alterations are just a few of the proposed explanations. It is becoming widely accepted that infertility shares a link with PC. Much of the link between infertility and PC is probably attributable to common genetic defects. This article provides an overview of PC and spermatogenic abnormalities. This study also investigates the link between male infertility and PC and uncovers the underlying reasons, risk factors, and biological mechanisms contributing to this association.

Perfluorooctanoic acid induces cell death in TM3 cells via the ER stress-mitochondrial apoptosis pathway

Perfluorooctanoic acid (PFOA) is an environmentally ubiquitous synthetic chemical highly persistent in organisms. PFOA exposure is pernicious to reproductive health as indicated by reports of male infertility. However, the PFOA toxicity mechanism to Leydig cells remains poorly understood. Therefore, this study aimed to investigate the toxicological events occurring in TM3 Leydig cells treated with PFOA (250, 500, 750µM) for 24h. PFOA was shown to significantly decrease cell viability resulting from inhibition of proliferation and elevation of apoptotic ratio in a dose dependent manner. Upregulation of pro-apoptotic gene expressions such as Bax, Bad, and p53, was observed in combination with an increase in the apoptosis-related protein levels of Bax, cleaved caspase-3, cleaved caspase-8, and phosphorylated p53. Furthermore, exposure of PFOA lead to mitochondrial damage involving mitochondrial membrane permeabilization. A release of cytochrome c and collapse of the mitochondrial membrane potential (∆Ψm) were observed compared to the untreated control. Additionally, PFOA stimulated unfolded protein response (UPR) upregulating ER stress marker, Bip/GRP78, and upregulated protein levels of UPR signal molecules IRE1, p-JNK, p-ERK1/2, p-p53, CHOP, and ERO1. Overall, the present study elucidated the ER stress-mitochondrial apoptosis pathway-related molecular mechanisms involved in PFOA-induced cell death in TM3 Leydig cells.

Dietary trends and the decline in male reproductive health

Over the twentieth century, male reproductive health has suffered a substantial decline, as evidenced by decreases in sperm counts and testosterone levels and increases in reproductive pathologies. At the same time, the prevalence of chronic diseases such as obesity, diabetes, and metabolic syndrome has risen dramatically. Metabolic and reproductive health are highly interconnected, suggesting that their respective trends are intertwined and, given the timeframe of such trends, environmental and not genetic factors are most likely to be the primary causes. Industrialization, which began in Europe in the mid-eighteenth century, has resulted in profound changes to our diet, lifestyle, and environment, many of which are causal factors in the rise in chronic diseases. Industrialization results in a nutrition transition from an agricultural unprocessed to a modern processed diet, incorporating increases in sugar, vegetable oils, ultra-processed foods, linoleic acid, trans-fats, and total energy. This dietary shift has incurred numerous adverse effects on metabolic and reproductive health, characterized by chronic inflammation, oxidative stress, and insulin resistance. Moreover, these effects appear to multiply across subsequent generations via epigenetic inheritance. Men's fertility is markedly affected by obesity and diabetes, with an increase in total energy via processed food intake arguably being the key factor driving the diabesity pandemic. In contrast, wholefoods rich in micronutrients and phytonutrients support male fertility and a healthy body weight. Therefore, men wanting to maximize their fertility should consider making positive dietary changes, such as replacing processed foods with unprocessed foods that support metabolic and reproductive health.

The protective effect of L-carnitine on testosterone synthesis pathway, and spermatogenesis in monosodium glutamate-induced rats

Background

Monosodium glutamate (MSG) is a food ingredient that is increasingly used commercially. MSG leads to oxidative stress, consequently suppressing steroid hormone production that causes defects in male reproductive system. This study aimed to evaluate the effect of L-carnitine as an antioxidant on testicular damage in MSG-induced male rats.

Methods

Sixty adult male Spargue-Dawley rats were randomly divided into six groups of ten as follows: control (water), sham (normal saline), L-carnitine (200 mg/kg b.w), MSG (3 g/kg b.w), MSG + L-carnitine 100 (3 g/kg b.w of MSG and 100 mg/kg b.w of L-carnitine), and MSG + L-carnitine 200 (3 g/kg b.w of MSG and 200 mg/kg b.w of L-carnitine). The treatment was administered by oral gavage for six months. Serum levels of Malondialdehyde (MDA), Total Anti-oxidant Capacity (TAC), LH, FSH, testosterone, and mRNA expressions of Star, Cyp11a1, and Hsd17b3 genes, and histological and stereological changes were assessed.

Results

L-carnitine led to a significant decrease in the level of MDA and a significant rise in the serum levels of TAC, LH, FSH, and mRNA expression of Star and Cyp11a1 compared to the MSG group (p < 0.05). Furthermore, stereological results indicated a significant increment in the number of sexual lineage cells, the total volume of the testis, length, diameter, and volume of seminiferous tubules, the height of the germinal epithelium, sperm count, and sperm motility (p < 0.05) in MSG + L-carnitine 200 compare to MSG group.

Conclusion

The study’s findings demonstrated that L-carnitine due to its anti-oxidant properties, ameliorated the reproductive abnormalities in the male rats exposed to MSG.

In vitro production of mouse morphological sperm in artificial testis bioengineered by 3D printing of extracellular matrix

Since autologous stem cell transplantation is prone to cancer recurrence, in vitro sperm production is regarded a safer approach to fertility preservation. In this study, the spermatogenesis process on testicular tissue extracellular matrix (T-ECM)-derived printing structure was evaluated. Ram testicular tissue was decellularized using a hypertonic solution containing triton and the extracted ECM was used as a bio-ink to print an artificial testis. Following cell adhesion and viability examination, pre-meiotic and post-meiotic cells in the study groups (as testicular suspension and co-culture with Sertoli cells) were confirmed by real-time PCR, flow-cytometry and immunocytochemistry methods. Morphology of differentiated cells was evaluated using transmission electron microscopy (TEM), toluidine blue, Giemsa, and hematoxylin and eosin (H&E) staining. The functionality of Leydig and Sertoli cells was determined by their ability for hormone secretion. The decellularization of testicular tissue fragments was successful and had efficiently removed the cellular debris and preserved the ECM compounds. High cell viability, colonization, and increased expression of pre-meiotic markers in cultured testicular cells on T-ECM-enriched scaffolds confirmed their proliferation. Furthermore, the inoculation of neonatal mouse testicular cells onto T-ECM-enriched scaffolds resulted in the generation of sperm. Morphology evaluation showed that the structure of these cells was quite similar to mature sperm with a specialized tail structure. The hormonal analysis also confirmed production and secretion of testosterone and inhibin B by Leydig and Sertoli cells. T-ECM printed artificial testis is a future milestone that promises for enhancing germ cell maintenance and differentiation, toxicology studies, and fertility restoration to pave the way for new human infertility treatments in the future.

Different Factors Are Associated With Sex Hormones and Leydig Cell Function in Israelis and Palestinians in Jerusalem

Total testosterone (TT) is known to influence health and virility in men. Among men from United States and Europe, numerous sociodemographic and lifestyle factors were reported to be associated with TT. However, associations with TT and Leydig cell function in the Middle East are poorly described. A cross-sectional, population-based sample had a structured interview, physical examinations, and blood tests in two hospitals in Jerusalem, Israel. A subsample (25- to 44-year-old men, n = 286: 124 Israelis, 162 Palestinians) had sex hormone measurements. The primary outcomes were TT and free testosterone/luteinizing hormone (FT/LH) ratio, representing Leydig cell function. Associations with sociodemographic and lifestyle factors, body mass index (BMI), and physical activity (PA) were evaluated using multivariable linear regression. Compared with Palestinians, Israelis had similar TT (4.81 vs. 5.09 ng/mL, p = .405) and higher FT/LH (31.2 vs. 25.8 ng/IU, p = .002). In ln-transformed values, marital status had a stronger association in Palestinians (P for interaction = 0.03). Age, BMI, and PA had a stronger association with TT in Israelis with significant interactions with ethnicity. BMI <25 and a higher PA quartile were associated with a higher TT (p < .001). Among Israelis, age (p = .007), married marital status (p = .007), and BMI <25 were significantly associated with FT/LH. No associations of any factors were identified among Palestinians. Associations with several modifiable factors identified in Western samples were replicated in Israelis and to a lesser degree in Palestinians. Different relationships of several factors with TT and FT/LH could result from ethnically diverse genetic, sociodemographic, and behavioral characteristics that warrant further research.

Association of age, hormonal, and lifestyle factors with the Leydig cell biomarker INSL3 in aging men from the EMAS (European Male Aging Study) cohort

BACKGROUND

Aging in men is accompanied by a broad range of symptoms, including sexual dysfunction, cognitive and musculo-skeletal decline, obesity, type 2 diabetes, cardiovascular disease and hypertension, organ degeneration/failure, and increasing neoplasia, some of which are associated with declining levels of Leydig cell-produced testosterone. High natural biological variance, together with multiple factors that can modulate circulating testosterone concentration, may influence its interpretation and clinical implications. INSL3 is a biomarker of Leydig cell function that might provide complementary information on testicular health and its downstream outcomes.

OBJECTIVES

To characterize INSL3 as a biomarker to assess gonadal status in aging men.

METHODS & MATERIALS

The large European multi-centre EMAS cohort of community-dwelling men was analysed to determine how INSL3 relates to a range of hormonal, anthropometric, and lifestyle parameters.

RESULTS & DISCUSSION

INSL3 declines cross-sectionally and longitudinally within individuals at approximately 15% per decade from age 40, unlike testosterone (1.9% per decade), which is partly compensated by increasing pituitary LH production. Importantly, lower INSL3 in younger men appears to persist with aging. Multiple regression analysis shows that, unlike testosterone, INSL3 is negatively dependent on LH and SHBG, and positively on FSH, suggesting a different mechanism of gonadotropic regulation. Circulating INSL3 is negatively associated with increased BMI or waist circumference, and with smoking, and unlike testosterone is not affected by weight loss in the obese. Geographic variation in mean INSL3 within Europe appears to be largely explained by differences in these parameters. The results allow the establishment of a European-wide reference range for INSL3 (95% confidence interval) adjusted for increasing age.

CONCLUSION

INSL3 is a constitutive biomarker of Leydig cell functional capacity, being a robust, reliably measurable peptide, not subject to the gonadotropin-dependent short-term regulation and within-individual variation of testosterone. This article is protected by copyright. All rights reserved.

Management of male factor infertility: position statement from the Italian Society of Andrology and Sexual Medicine (SIAMS) : Endorsing Organization: Italian Society of Embryology, Reproduction, and Research (SIERR)

PURPOSE

Infertility affects 15-20% of couples and male factors are present in about half of the cases. For many aspects related to the diagnostic and therapeutic approach of male factor infertility, there is no general consensus, and the clinical approach is not uniform.

METHODS

In the present document by the Italian Society of Andrology and Sexual Medicine (SIAMS), endorsed by the Italian Society of Embryology, Reproduction, and Research (SIERR), we propose evidence-based recommendations for the diagnosis, treatment, and management of male factor infertility to improve patient and couple care.

RESULTS

Components of the initial evaluation should include at minimum medical history, physical examination, and semen analysis. Semen microbiological examination, endocrine assessment, and imaging are suggested in most men and recommended when specific risk factors for infertility exist or first-step analyses showed abnormalities. Full examination including genetic tests, testicular cytology/histology, or additional tests on sperm is clinically oriented and based on the results of previous investigations. For treatment purposes, the identification of the specific cause and the pathogenetic mechanism is advisable. At least, distinguishing pre-testicular, testicular, and post-testicular forms is essential. Treatment should be couple-oriented, including lifestyle modifications, etiologic therapies, empirical treatments, and ART on the basis of best evidence and with a gradual approach.

CONCLUSION

These Guidelines are based on two principal aspects: they are couple-oriented and place high value in assessing, preventing, and treating risk factors for infertility. These Guidelines also highlighted that male infertility and in particular testicular function might be a mirror of general health of a man.

The Fate of Leydig Cells in Men with Spermatogenic Failure

The steroidogenic cells in the testicle, Leydig cells, located in the interstitial compartment, play a vital role in male reproductive tract development, maintenance of proper spermatogenesis, and overall male reproductive function. Therefore, their dysfunction can lead to all sorts of testicular pathologies. Spermatogenesis failure, manifested as azoospermia, is often associated with defective Leydig cell activity. Spermatogenic failure is the most severe form of male infertility, caused by disorders of the testicular parenchyma or testicular hormone imbalance. This review covers current progress in knowledge on Leydig cells origin, structure, and function, and focuses on recent advances in understanding how Leydig cells contribute to the impairment of spermatogenesis.

Expression of G-Protein-Coupled Estrogen Receptor (GPER) in Whole Testicular Tissue and Laser-Capture Microdissected Testicular Compartments of Men with Normal and Aberrant Spermatogenesis

Simple Summary

Nowadays, there is no doubt that estrogens play an important role in male reproduction, affecting testicular cell differentiation, proliferation, apoptosis and metabolism. It is also widely believed that intratesticular balance of androgens and estrogens is crucial for the testicular development and function and that the increased testicular estrogen production may be associated with spermatogenic failure. There is also growing epidemiological evidence that the exposure of men to endocrine disruptors demonstrating estrogenic activity (xenoestrogens) may lead to impairment of male fertility via interference with estrogen signaling pathways. Besides the two classical nuclear estrogen receptors, the membrane-bound G protein-coupled estrogen receptor (GPER) was described in human testicular tissue. However, there are little data on its expression in testes with disturbed spermatogenesis. In this study, we investigated the GPER expression pattern in biopsies of azoospermic men with complete and aberrant spermatogenesis. Our results showed an increased expression of the GPER in testes with impaired spermatogenesis. Moreover, they indicate a possible involvement of estrogen signaling through GPER in disturbed function of Sertoli cells—the cells that support spermatogenic process.

Abstract

In this study, we retrospectively investigated GPER expression in biopsies of azoospermic men with complete (obstructive azoospermia—OA) and aberrant spermatogenesis (nonobstructive azoospermia—NOA). Each biopsy was histologically evaluated with morphometry. The testicular GPER expression was analyzed by the immunohistochemistry and RT-PCR technique in the whole testicular tissue and in seminiferous tubules and Leydig cells after laser-capture microdissection. In laser-microdissected compartments, we also analyzed transcriptional expression of selected Leydig (CYP17A1, HSD17B3, StAR) and Sertoli cell (AMH, SCF, BMP4) function markers. Immunohistochemical staining revealed expression of GPER in the cytoplasm of Leydig and Sertoli cells. Its stronger intensity was observed in Sertoli cells of NOA biopsies. The RT-PCR analysis of the GPER mRNA level unequivocally showed its increased expression in seminiferous tubules (i.e., Sertoli cells), not Leydig cells in NOA biopsies. This increased expression correlated positively with the transcriptional level of AMH—a marker of Sertoli cell immaturity, as well as FSH serum level in NOA but not in the OA group. Our results clearly demonstrate altered GPER expression in testes with primary spermatogenic impairment that might be related to Sertoli cell maturity/function.

Regenerative medicine for male infertility: a focus on stem cell niche injury models

Stem and progenitor cells located within stem cell niches maintain the renewal and regeneration of tissues and organs throughout the life of an adult organism. Stem cell niche component dysfunction might alter the activity of stem cells and ultimately lead to the development of difficult-to-treat chronic or acute disorders. Of note, some cases of idiopathic male infertility, a highly prevalent diagnosis with no specific treatment options, might be associated with a spermatogonial stem cell(SSC) niche disturbance. To overcome this disease entity, approaches aiming at launching the regeneration of an altered stem cell niche are worth considering. Particularly, mesenchymal stromal cells (MSCs) or their secretome might fulfill this task due to their promising contribution in recovering injured stem cell niches. However, the successful application of MSC-based treatment is limited by the uncovered mechanisms of action of MSCs and their secretome. Specific animal models should be developed or adapted to reveal the role of MSCs and their secretome in a stem cell niche recovery. In this review, in a bid to consider MSCs and their secretome as a therapeutic regenerative approach for idiopathic male infertility we focus on the rationale of SSC niche injury modeling.

Bisphenol S exposure induces cytotoxicity in mouse Leydig cells

Bisphenol S (BPS), an increasingly used alternative to bisphenol A, has been linked to testosterone deficiency and male reproductive dysfunction in laboratory animals. This study aimed to examine the cytotoxicity of BPS exposure to Leydig cells and to investigate its possible mechanisms. After treatment with BPS (100, 200 and 400 μM) for 48 h in vitro, TM3 mouse Leydig cells exhibited a dose-dependent decrease in the viability. Furthermore, BPS challenge triggered oxidative stress manifested by compromised activities of superoxide dismutase and catalase with exaggerated formation of reactive oxygen species. Especially, BPS exposure resulted in augmented mitochondrial permeability transition pore opening, dissipated mitochondrial membrane potential and reduced ATP generation, along with an altered energy metabolism. Moreover, BPS stimulation enhanced BAX expression and caspase-3 activity and inhibited BCL-2 expression. In addition, BPS-treated TM3 cells showed an accumulation of autophagic vacuoles, together with increased Beclin1 and P62 expression and elevated LC3B-II/LC3B-I ratio. These results demonstrated that in vitro exposure to BPS exerted cytotoxicity to TM3 Leydig cells through inducing oxidative stress, mitochondrial impairment, autophagic disturbance and apoptosis.

Single sperm vitrification with permeable cryoprotectant-free medium is more effective in patients with severe oligozoospermia and azoospermia

Testicular sperm extraction (TESE) is an invasive surgery for achieving the spermatozoa in cases with azoospermia. In these patients, the number of retrieved spermatozoa is limited and the optimal cryo-storage is very critical for their fertility preservation. Therefore, single sperm vitrification has been introduced for preservation of low number of spermatozoa. The goal was to assess the efficacy of sperm freezing medium (SFM) and sucrose medium as cryoprotectants for single sperm vitrification in cases with severe oligozoospermia and azoospermia. A total of 20 ejaculates from severe oligozoospermia and 20 testicular samples from azoospermia were processed. Twenty-five sperm cells were collected using ICSI injection pipette and transferred to a cryoprotectant droplet placed on the Cryotech, then vitrified by plunging in liquid nitrogen. Sperm motility, viability, fine-morphology, mitochondrial activity and DNA fragmentation index (DFI) were assessed before and after vitrification. Sperm motility, viability and the percentage of cells with mitochondrial activity were significantly decreased after vitrification in both severe oligozoospermic and testicular samples in either cryoprotectants. However, the rates of post-warm sperm motility and the cells with mitochondrial activity increased significantly in sucrose medium in both severe oligozoospermic and testicular samples compared to SFM. In testicular samples, the DFI of spermatozoa vitrified in SFM was significantly higher than those vitrified with sucrose medium. Sperm motility, viability, mitochondrial activity, and DNA integrity were better preserved in sucrose medium than SFM after single cell vitrification. The presented method may be a useful candidate for successful freezing of individual sperm cells in clinical setting.

Leydig Cells in Patients with Non-Obstructive Azoospermia: Do They Really Proliferate?

Background: Non-obstructive azoospermia (NOA) is a form of male infertility caused by disorders of the testicular parenchyma and impaired spermatogenesis. This study aimed to investigate the nature of Leydig cell changes in patients with NOA, especially whether their actual proliferation occurred. Methods: 48 testicular biopsies from infertile patients with NOA and 24 testicular biopsies originating from azoospermic patients suffering from obstructive azoospermia (OA) were included in the study. Leydig cells and their possible proliferative activity were analysed by immunohistochemistry and morphometry (stereology). Results: Unlike in the OA group, Leydig cells in NOA patients were sometimes organised into larger clusters and displayed an abundant cytoplasm/hypertrophy. Moreover, significant fibrosis of the interstitial compartment was demonstrated in some NOA samples, often accompanied by inflammatory cells. Stereological analysis showed no increase/proliferation of Leydig cells; on the contrary, these cells decreased in number in the NOA group. Conclusions: The decrease in the number of Leydig cells can be explained by previous inflammatory changes within the testicular interstitium and consequent interstitial fibrosis. The interstitial fibrosis might have a deteriorating effect on Leydig cells.

Phthalate Toxicity in Rats and Its Relation to Testicular Dysgenesis Syndrome in Humans

This work describes the relevance of toxicology studies of environmental chemicals, with a focus on phthalates, for a hypothesis that certain human male reproductive disorders and diseases have a common etiology of disturbance of normal development in utero. The "Testicular Dysgenesis Syndrome" hypothesis in humans has parallels in male reproductive tract abnormalities and microscopic lesions reported for phthalate toxicity in rats. Additionally, this work describes the histological findings of abnormal testicular development (testicular dysgenesis) in rats as compared to those in humans, as well as potential findings in rats at different ages, from the embryo to the adult.

European Association of Urology Guidelines on Male Sexual and Reproductive Health: 2021 Update on Male Infertility

CONTEXT

The European Association of Urology (EAU) has updated its guidelines on sexual and reproductive health for 2021.

OBJECTIVE

To present a summary of the 2021 version of the EAU guidelines on sexual and reproductive health, including advances and areas of controversy in male infertility.

EVIDENCE ACQUISITION

The panel performed a comprehensive literature review of novel data up to January 2021. The guidelines were updated and a strength rating for each recommendation was included that was based either on a systematic review of the literature or consensus opinion from the expert panel, where applicable.

EVIDENCE SYNTHESIS

The male partner in infertile couples should undergo a comprehensive urological assessment to identify and treat any modifiable risk factors causing fertility impairment. Infertile men are at a higher risk of harbouring and developing other diseases including malignancy and cardiovascular disease and should be screened for potential modifiable risk factors, such as hypogonadism. Sperm DNA fragmentation testing has emerged as a novel biomarker that can identify infertile men and provide information on the outcomes from assisted reproductive techniques. The role of hormone stimulation therapy in hypergonadotropic hypogonadal or eugonadal patients is controversial and is not recommended outside of clinical trials. Furthermore, there is insufficient evidence to support the widespread use of other empirical treatments and surgical interventions in clinical practice (such as antioxidants and surgical sperm retrieval in men without azoospermia). There is low-quality evidence to support the routine use of testicular fine-needle mapping as an alternative diagnostic and predictive tool before testicular sperm extraction (TESE) in men with nonobstructive azoospermia (NOA), and either conventional or microdissection TESE remains the surgical modality of choice for men with NOA.

CONCLUSIONS

All infertile men should undergo a comprehensive urological assessment to identify and treat any modifiable risk factors. Increasing data indicate that infertile men are at higher risk of cardiovascular mortality and of developing cancers and should be screened and counselled accordingly. There is low-quality evidence supporting the use of empirical treatments and interventions currently used in clinical practice; the efficacy of these therapies needs to be validated in large-scale randomised controlled trials.

PATIENT SUMMARY

Approximately 50% of infertility will be due to problems with the male partner. Therefore, all infertile men should be assessed by a specialist with the expertise to not only help optimise their fertility but also because they are at higher risk of developing cardiovascular disease and cancer long term and therefore require appropriate counselling and management. There are many treatments and interventions for male infertility that have not been validated in high-quality studies and caution should be applied to their use in routine clinical practice.

Kiss1 is differentially regulated in male and female mice by the homeodomain transcription factor VAX1

Regulation of Kiss1 transcription is crucial to the development and function of the reproductive axis. The homeodomain transcription factor, ventral anterior homeobox 1 (VAX1), has been implicated as a potential regulator of Kiss1 transcription. However, it is unknown whether VAX1 directly mediates transcription within kisspeptin neurons or works indirectly by acting upstream of kisspeptin neuron populations. This study tested the hypothesis that VAX1 within kisspeptin neurons regulates Kiss1 gene expression. We found that VAX1 acts as a repressor of Kiss1 in vitro and within the male arcuate nucleus in vivo. In female mice, we found that the loss of VAX1 caused a reduction in Kiss1 expression and Kiss1-containing neurons in the anteroventral periventricular nucleus at the time of the preovulatory luteinizing hormone surge, but was compensated by an increase in Kiss1-cFos colocalization. Despite changes in Kiss1 transcription, gonadotropin levels were unaffected and there were no impairments to fertility.

Study of Semen Quality, Reproductive Hormone Levels, and Lipid Levels in Men From Arkhangelsk, a City in North of European Russia

Male populations in the European North of Russia have not previously been investigated for semen quality. The aim of this study was to evaluate semen parameters, reproductive hormone levels, and lipid levels in volunteers from the general urban population of the European North of Russia, to compare the data published for men from the neighboring Northern or Eastern European countries, and to evaluate associations between sperm quality and serum hormonal and lipid levels. Ninety-nine volunteers aged 23-63 years residing in the city of Archangelsk were enrolled in the study. All men had blood samples drawn and completed a questionnaire concerning their health status and lifestyle; 90 men delivered semen samples. The medians for semen volume, sperm concentration, progressive motility, and normal morphology were 3.0 ml, 42.12 million/ml, 43.8%, and 6.5%, respectively. Sperm parameters below normal threshold values were found in 38.9% of participants. It seems that the sperm quality in our study group was slightly worse than in men from Finland, Norway, Sweden, or Estonia, but very similar to that in men from Denmark or Poland. The significant negative correlations of luteinizing hormone levels and positive correlations of inhibin B levels with sperm concentration and progressive motility were revealed. Higher levels of luteinizing hormone and lower levels of inhibin B were found in participants with impaired compared to normal sperm quality. No reliable links were found between serum total cholesterol, triglyceride, high and low-density lipoprotein cholesterol, and semen parameters.

Endocrine Follow-Up of Men with Non-Obstructive Azoospermia Following Testicular Sperm Extraction

Testicular sperm extraction (TESE) is a surgical procedure which, combined with intracytoplasmic sperm injection, constitutes the main treatment for achieving biological parenthood for patients with infertility due to non-obstructive azoospermia (NOA). Although it is effective, TESE procedures might cause structural testicular damage leading to Leydig cell dysfunction and, consequently, temporary or even permanent hypogonadism with long-term health consequences. To a lesser extent, the same complications have been reported for microdissection TESE, which is considered less invasive. The resulting hypogonadism is more profound and of longer duration in patients with Klinefelter syndrome compared with other NOA causes. Most studies on serum follicle-stimulating hormone and luteinizing hormone concentrations negatively correlate with total testosterone concentrations, which depends on the underlying histology. As hypogonadism is usually temporary, and a watchful waiting approach for about 12 months postoperative is suggested. In cases where replacement therapy with testosterone is indicated, temporary discontinuation of treatment may promote the expected recovery of testosterone secretion and revise the decision for long-term treatment.

The effects of Vitamin D3 supplementation on Spermatogram and endocrine factors in asthenozoospermia infertile men: a randomized, triple blind, placebo-controlled clinical trial

OBJECTIVE

Evaluate the effects of vitamin D3 (VD3) on sperm parameters and endocrine markers in infertile men with asthenozoospermia.

MATERIALS AND METHODS

This randomized, triple-masking, placebo-controlled clinical trial conducted on 86 asthenozoospermia infertile men with serum 25 hydroxy vitamin D3 (25(OH)VD3) < 30 ng/ml in the infertility clinic of Ahvaz Jahad daneshgahi, Iran. Patients were randomly allocated to groups A and B, who received daily 4000 IU VD3 and matching placebo respectively for 3 months. Demographic data, dietary intake, physical activity, sun exposure, anthropometric indices, serum 25(OH)VD3, luteinizing hormone (LH), follicle-stimulating hormone (FSH), total testosterone (T), estradiol (E2),, sex hormone-binding globulin (SHBG), free androgen index (FAI = T/SHBG. 100), T/LH and T/E2 ratios, prolactin (PRO), parathyroid hormone (PTH), osteocalcin (OCN), phosphorus and sperm parameters were assessed.

RESULTS

Three months VD3 supplementation with 4000 IU/day had no significant effects body weight, body mass index (BMI), waist circumference (WC), body fat (BF), serum, OCN, LH, FSH, T, E2, SHBG, PRO, T/E2 ratio, FAI, semen volume, sperm count and normal sperm morphology. It increases serum 25(OH)VD3, PTH and phosphorus and seminal and serum calcium, T/LH ratio and total and progressive sperm motility and decreased significantly compared to the baseline and placebo group.

CONCLUSION

VD3 supplementation may affect sperm motility in men with asthenozoospermia and serum 25(OH)VD3 < 30 ng/ml.

TRIAL REGISTRATION

Iran Clinical Trials Registry, ID: IRCT20151128025274N4, registered on 28 March 2018, URL of trial registry record: https://www.irct.ir/trial/29983.

Evaluation of the effect of vitamin D supplementation on spermatogram, seminal and serum levels of oxidative stress indices in asthenospermia infertile men: a study protocol for a triple-blind, randomized controlled trial

BACKGROUND

It is suggested that vitamin D may have a beneficial role in male reproduction. The male reproductive system is a target tissue for vitamin D. This study will aim to evaluate the effects of vitamin D supplementation on sperm parameters, seminal and serum levels of oxidative stress and serum endocrine factors in asthenospermia infertile men.

METHODS/DESIGN

This randomized, triple-blind, placebo-controlled clinical trial will be conducted on 86 infertile men with idiopathic asthenozoospermia (the mobility of sperm < 40% and rapid progressive sperm motility < 32%), with serum levels of vitamin D less than 30 ng / ml in the "Infertility Clinic of Ahvaz Jahad daneshgahi", Iran.

MAIN OUTCOMES MEASURE (S)

Demographic data, dietary intake, physical activity, sun exposure, anthropometric indices, serum and seminal levels of MDA (Malondialdehyde), 8-hydroxy-2- Dioxy Guanosine (8-OHDG), Total Antioxidant Capacity (TAC) and calcium, sperm DNA fragmentation index (DFI), serum 25-OHD, luteinizing hormone (LH), follicle-stimulating hormone (FSH), total testosterone (T), estradiol (E2), sex hormone-binding globulin (SHBG), free androgen index (FAI = T/SHBG. 100), T/LH and T/E2 ratios, prolactin (PRO), parathyroid hormone (PTH), osteocalcin (OCN), phosphorus and sperm parameters.

DISCUSSION

The deficiency of vitamin D as an antioxidant is common all over the world. Numerous observational studies have shown a positive association between vitamin D levels and semen quality. However, few clinical studies have been conducted in this area. So considering with the high prevalence of this antioxidant deficiency specifically in infertile men, it seems that the supplementation of vitamin D in infertile men with insufficient levels or deficiency may improve the status of oxidative stress and thereby may affect sperm parameters and endocrine factors involved in male fertility.

TRIAL REGISTRATION

Iran Clinical Trials Registry, ID: IRCT20151128025274N4 , registered on 28 March 2018.

RANKL regulates male reproductive function

Infertile men have few treatment options. Here, we demonstrate that the transmembrane receptor activator of NF-kB ligand (RANKL) signaling system is active in mouse and human testis. RANKL is highly expressed in Sertoli cells and signals through RANK, expressed in most germ cells, whereas the RANKL-inhibitor osteoprotegerin (OPG) is expressed in germ and peritubular cells. OPG treatment increases wild-type mouse sperm counts, and mice with global or Sertoli-specific genetic suppression of Rankl have increased male fertility and sperm counts. Moreover, RANKL levels in seminal fluid are high and distinguishes normal from infertile men with higher specificity than total sperm count. In infertile men, one dose of Denosumab decreases RANKL seminal fluid concentration and increases serum Inhibin-B and anti-Müllerian-hormone levels, but semen quality only in a subgroup. This translational study suggests that RANKL is a regulator of male reproductive function, however, predictive biomarkers for treatment-outcome requires further investigation in placebo-controlled studies.

Male seminal parameters are not associated with Leydig cell functional capacity in men

BACKGROUND

Insulin-like peptide 3 (INSL3) is a constitutive, secreted peptide produced in the male uniquely by the Leydig cells of the testes. It is a biomarker for Leydig cell functional capacity, which is a measure of the numbers and differentiation status of these steroidogenic cells and lacks the biological and technical variance of the steroid testosterone. This retrospective study was carried out to examine the relationship between seminal parameters and the Leydig cell compartment, and secondarily to assess other factors responsible for determining Leydig cell functional capacity.

METHODS

INSL3 was assessed together with seminal, anthropometric, and hormonal parameters in a Swedish cohort of 18-year-old men, representing the average population, and in a smaller, more heterogeneous cohort of men visiting an Australian infertility clinic.

RESULTS AND DISCUSSION

Average INSL3 concentration at 18 years is greater than that reported at younger or older ages and indicated a large 10-fold variation. In neither cohort was there a relationship between INSL3 concentration and any semen parameter. For the larger, more uniform Swedish cohort of young men, there was a significant negative relationship between INSL3 and BMI, supporting the idea that adult Leydig cell functional capacity may be established during puberty. In both cohorts, there was a significant relationship between INSL3 and FSH, but not LH concentration. No relationship was found between INSL3 and androgen receptor trinucleotide repeat polymorphisms, reinforcing the notion that Leydig cell functional capacity is unlikely to be determined by androgen influence alone. Nor did INSL3 correlate with the T/LH ratio, an alternative measure of Leydig cell functional capacity, supporting the view that these are independent measures of Leydig cell function.

Testicular steroid sulfatase overexpression is associated with Leydig cell dysfunction in primary spermatogenic failure

BACKGROUND

Decreased testosterone (T) to LH ratio and increased 17β-estradiol (E2) serum concentrations represent a common finding among patients with severe spermatogenic failure, suggesting a concurrent Leydig cell steroidogenic dysfunction. Aromatase overexpression has been associated with increased serum and intratesticular E2 in these patients. However, it is unknown whether the sulfatase pathway contributes to the increased availability of active estrogens in patients with primary spermatogenic failure.

OBJECTIVES

To assess estrogen sulfotransferase (SULT1E1) and steroid sulfatase (STS) mRNA abundance in testicular tissue of patients with Sertoli cell-only syndrome (SCOS) and normal tissues, its association with serum and intratesticular hormone levels, and to explore the mRNA and protein testicular localization of both enzymes.

MATERIALS AND METHODS

Testicular tissues of 23 subjects with SCOS (cases) and 22 patients with obstructive azoospermia and normal spermatogenesis (controls) were obtained after biopsy. SULT1E1 and STS transcripts accumulation was quantified by RT-qPCR. For mRNA and protein localization, we performed RT-qPCR in Leydig cell clusters and seminiferous tubules isolated by laser-capture microdissection and immunofluorescence in testicular tissues. Serum and intratesticular hormones were measured by immunoradiometric assays.

RESULTS

SULT1E1 mRNA accumulation was similar in both groups. The amount of STS mRNA was higher in cases (p = 0.007) and inversely correlated with T/LH ratio (r = -0.402; p = 0.02). Also, a near significant correlation was observed with intratesticular E2 (r = 0.329, p = 0.057), in agreement with higher intratesticular E2 in cases (p < 0.001). Strong STS immunoreaction was localized in the wall of small blood vessels but not in Leydig cells. Both SULT1E1 and STS mRNA abundance was similar in Leydig cell clusters and the tubular compartment, except for lower SUTL1E1 mRNA in the seminiferous tubules of SCOS patients (p = 0.001).

CONCLUSIONS

Our results suggest that an unbalance of the STS/SULT1E1 pathway contributes to the testicular hyperestrogenic microenvironment in patients with primary spermatogenic failure and Leydig cell dysfunction.

Regional difference in semen quality of young men: a review on the implication of environmental and lifestyle factors during fetal life and adulthood

The prevalence of low semen quality and the incidence of testicular cancer have been steadily increasing over the past decades in different parts of the World. Although these conditions may have a genetic or epigenetic origin, there is growing evidence that multiple environmental and lifestyle factors can act alone or in combination to induce adverse effects. Exposure to these factors may occur as early as during fetal life, via the mother, and directly throughout adulthood after full spermatogenic capacity is reached. This review aims at providing an overview of past and current trends in semen quality and its relevance to fertility as well as a barometer of men’s general health. The focus will be on recent epidemiological studies of young men from the general population highlighting geographic variations in Europe. The impact of some lifestyle and environmental factors will be discussed with their role in both fetal life and adulthood. These factors include smoking, alcohol consumption, psychological stress, exposure to electromagnetic radiation, and Endocrine Disrupting Chemicals (EDCs). Finally, the challenges in investigating the influence of environmental factors on semen quality in a fast changing world are presented.

A history of cryptorchidism is associated with impaired testicular function in early adulthood: a cross-sectional study of 6376 men from the general population

STUDY QUESTION

Is there a difference in testicular function in early adulthood between men born with cryptorchidism and men born with normally descended testes?

SUMMARY ANSWER

In men from the general population, a history of cryptorchidism was associated with lower total testis volume and impaired semen quality as well as altered serum levels of reproductive hormones.

WHAT IS KNOWN ALREADY

The association between cryptorchidism and testicular function is well documented in studies based on sub-fertile or infertile men recruited from a clinical setting. However, the association has not previously been investigated in men from the general population, who were unselected regarding fertility status.

STUDY DESIGN, SIZE, DURATION

This is a cross-sectional population-based study of 6376 young Danish men examined from 1996 to 2017.

PARTICIPANTS/MATERIALS, SETTING, METHODS

This study is based on young men from the greater Copenhagen area, Denmark (median age of 19 years) who were unselected regarding fertility status and semen quality. The young men delivered a semen sample, had a blood sample drawn and underwent a physical examination including assessment of testis volume. Participants completed a questionnaire regarding cryptorchidism at birth, current lifestyle and their mother’s pregnancy, after consulting their mother. The differences in markers of testicular function, including testis volume, semen parameters and reproductive hormones between men with and without a history of cryptorchidism were investigated with multiple linear regression analyses.

MAIN RESULTS AND THE ROLE OF CHANCE

The participation rate was 24% for the entire study period. Overall, a history of cryptorchidism was associated with reduced testicular function. In the adjusted models, a history of cryptorchidism was associated with a 3.5 ml lower total testis volume, determined by orchidometer (P &lt; 0.001), 28% lower sperm concentration (95% CI: −37 to −20) and 26% lower inhibin B/FSH ratio (95% CI: −50 to −22) compared to men without a history of cryptorchidism, suggesting a reduced spermatogenetic capacity. Men with a history of cryptorchidism also had a slightly reduced Leydig cell function expressed as a 6% lower testosterone/LH ratio (95% CI: −12 to −0.7). The significant effect sizes and different markers of testicular function pointing in the same direction across the different models based on a large sample size support that the results are not chance findings.

LIMITATIONS, REASONS FOR CAUTION

Information on cryptorchidism at birth and treatment modus was obtained by retrospective self-report, and each participant only delivered one semen sample.

WIDER IMPLICATIONS OF THE FINDINGS

The results suggest that men with a history of cryptorchidism could be at increased risk of experiencing fertility problems. However, among these men there is a wide variation in semen quality and further research is needed in order to identify the subgroup of boys born with cryptorchidism who are at the greatest risk of impaired semen quality when reaching adulthood.

STUDY FUNDING/COMPETING INTEREST(S)

The study received financial support from the Research fund of Rigshospitalet, Copenhagen University Hospital; the European Union (Contract numbers BMH4-CT96-0314, QLK4-CT-1999-01422, QLK4-CT-2002-00603. FP7/2007-2013, DEER Grant agreement no. 212844); the Danish Ministry of Health; the Danish Environmental Protection Agency; A.P. Møller and wife Chastine McKinney Møllers Foundation; and Svend Andersens Foundation. None of the founders had any role in the study design, collection, analysis or interpretation of data, writing of the paper or publication decisions. The authors have nothing to declare.

TRIAL REGISTRATION NUMBER

N/A.

Impact of psychological stress measured in three different scales on testis function: A cross-sectional study of 1362 young men

BACKGROUND

Studies have reported associations between psychological stress and semen quality, but most have been performed on selected populations using different stress measures. Thus, it is uncertain which stress scale best quantifies the effects of stress on testicular function.

OBJECTIVE

To study the association between three different measures of stress and testicular function in young men.

MATERIAL AND METHODS

In total, 1362 men (median age 19 years) delivered semen and blood samples. They also answered a questionnaire including information from three stress scales: Stress Symptoms, Stressful Life Events and Perceived Stress. Various statistical analyses for associations between stress and testicular function (semen quality and reproductive hormones) were performed.

RESULTS

Perceived Stress was negatively associated with sperm concentration, total count and motility and positively associated with serum FSH. Men with the highest scores (>30 points) had 38% (95% CI 3-84%) lower sperm concentration, 42% (95% CI 5-91%) lower total count and 22% (95% CI 2-32%) lower proportion of motile spermatozoa than men with the lowest scores (0-10 points). For the stress symptoms score, men with highest scores (>95th percentile vs. lower) had lower sperm concentration, total sperm count, motility and serum Inhibin-B/FSH-ratio. Although men with highest stress levels were characterized by an unhealthier lifestyle, adjusting for lifestyle factors did not attenuate results suggesting that the associations between stress and testicular function were not mediated by lifestyle. Stressful Life Events were not associated with testicular function.

DISCUSSION AND CONCLUSION

The linear association between Perceived Stress and semen parameters and lack of dose-response association for the other two stress scales indicated that perceived stress was the most sensitive marker of stress affecting semen quality in young men. The lack of associations between Stressful Life Events and testis function confirmed that the perception of stressful events rather than the stressful event per se matters.

High serum FSH is not a risk factor for low bone mineral density in infertile men

BACKGROUND

Male infertility is associated with a higher long-term morbidity and mortality risk. However, it is not clear which diseases are contributing to this risk. Osteoporosis is a possible factor, as it is a frequent disease and sex steroids regulate both fertility and bone health. Furthermore, there are data indicating that high FSH levels in women are related to low bone mineral density (BMD), independent of estradiol levels. As infertile men often have increased FSH, already from a young age, this could be a risk factor for impaired bone health in later life.

METHODS

One hundred and thirty-seven men with a history of male factor infertility due to spermatogenic failure (SgF men) as well as a control group of 70 men from couples treated with IVF for female factor infertility (non-SgF men) were included in a long-term follow-up study. Men with explained infertility, including testosterone deficiency, were not included. Data from baseline fertility investigations were retrieved from the patient files of the SgF men. At follow-up hormonal and semen analysis were performed and axial, femoral and total body BMD was measured by dual X-ray absorptiometry in all men. Multiple linear regression was used to assess differences between SgF and non-SgF men and to study associations between FSH levels and BMD.

RESULTS

Median follow-up time was 14.8 years (5th-95th percentile 11.3-18.2) after fertility assessment for SgF men and 15.6 years (12.1-18.5) for non-SgF men (p = 0.033). When comparing the two groups, no significant differences in total T, free T or E2 levels were apparent at follow-up. As expected, LH and FSH were higher in SgF men ((median (5th-95th percentile)) for LH (IU/L): 4.3 (2.2-13.6) for SgF men and 3.0 (1.4-5.8) for non-SgF men (p < 0.001); FSH (IU/L): 9.8 (2.8-35.5) versus 3.7 (1.6-8.7); p < 0.001), and inhibin B and semen parameters were lower in SgF men. There were no differences in BMD between the two groups at follow-up. Furthermore, both groups had median Z-scores close to zero at all sites, indicating that BMD is not different when compared to age-matched healthy men. In SgF men, neither baseline FSH, nor FSH at follow-up, was associated with BMD at the different sites at follow-up.

CONCLUSION

Men with spermatogenic failure are not at increased risk for impaired bone health when middle aged. Furthermore, infertile men with high FSH levels do not have lower BMD.

Prospects for FSH Treatment of Male Infertility

CONTEXT

Despite the new opportunities provided by assisted reproductive technology (ART), male infertility treatment is far from being optimized. One possibility, based on pathophysiological evidence, is to stimulate spermatogenesis with gonadotropins.

EVIDENCE ACQUISITION

We conducted a comprehensive systematic PubMed literature review, up to January 2020, of studies evaluating the genetic basis of follicle-stimulating hormone (FSH) action, the role of FSH in spermatogenesis, and the effects of its administration in male infertility. Manuscripts evaluating the role of genetic polymorphisms and FSH administration in women undergoing ART were considered whenever relevant.

EVIDENCE SYNTHESIS

FSH treatment has been successfully used in hypogonadotropic hypogonadism, but with questionable results in idiopathic male infertility. A limitation of this approach is that treatment plans for male infertility have been borrowed from hypogonadism, without daring to overstimulate, as is done in women undergoing ART. FSH effectiveness depends not only on its serum levels, but also on individual genetic variants able to determine hormonal levels, activity, and receptor response. Single-nucleotide polymorphisms in the follicle-stimulating hormone subunit beta (FSHB) and follicle-stimulating hormone receptor (FSHR) genes have been described, with some of them affecting testicular volume and sperm output. The FSHR p.N680S and the FSHB -211G>T variants could be genetic markers to predict FSH response.

CONCLUSIONS

FSH may be helpful to increase sperm production in infertile men, even if the evidence to recommend the use of FSH in this setting is weak. Placebo-controlled clinical trials, considering the FSHB-FSHR haplotype, are needed to define the most effective dosage, the best treatment length, and the criteria to select candidate responder patients.

Cryopreservation of single-sperm: where are we today?

BACKGROUND

Patients with severe oligospermia and nonobstructive azoospermia have very limited numbers of viable sperm in their epididymal and testicular samples. Thus, cryopreservation of their sperm is performed to avoid repeated sperm retrievals and to preserve their sperm from any side effects of any treatment regimens.

MAIN BODY

The development of intracytoplasmic sperm injection technology has extended the therapeutic capacity of assisted reproductive technology for men with azoospermia via the surgical or percutaneous isolation of sperm from the testis/epididymis. The conventional cryopreservation techniques are inadequate for preserving individually selected sperm. The technique for freezing single sperm was first developed in 1997 and has been explored from the perspective of frozen carriers, freezing programs, and cryoprotectant formulations. Among these methods, advances in frozen carriers have directly improved single-sperm freezing technology. In this review, we evaluate the different technologies for the cryopreservation of single sperm by discussing the advantages and disadvantages of different freezing methods, their clinical applications, and the outcomes for a range of frozen carriers.

CONCLUSION

Our review article describes the latest and current technologies implemented for the cryopreservation of single sperm that could potentially benefit patients with severe oligospermia and who rarely have any sperm in their ejaculate. This review provides a platform to understand the process and pitfalls of single-sperm cryopreservation to ensure further improvements in the cryopreservation technology in future studies.

Increased Gonadotropins and prolactin are linked to infertility in males

Infertility has become a significant issue among married couples worldwide. The association of variations in reproductive hormones with infertility is evaluated at a tertiary care hospital in North India. A total of 220 infertile males having infertility longer than one year (cases) and 220 age-matched fertile males with confirmed paternity in past two to three years (controls) were enrolled for the study. Serum levels of LH, FSH, testosterone and PRL were measured by Roche e411 autoanalyzer using electrochemiluminescense immunoassay technique. Significant higher levels of serum hormone (mean±SD) were found in cases vs. controls; LH (9.02±7.81 vs. 5.22±1.45 mIU/ml), FSH (11.45±14.02 vs. 4.09±1.62 mIU/ml) and PRL (199.08±80.79 vs. 127.23±81.64 µIU/ml). However, the serum testosterone level was significantly low in cases associated with male infertility (4.62±2.03 vs. 6.82±2.79 ng/ml). LH, FSH and PRL levels were significantly increased in azoospermic, oligozoospermic and asthenozoospermic infertile males while FSH and PRL were significantly elevated in normozoospermic infertile group. Conversely, mean serum testosterone levels were significantly low in all infertile subgroups in comparison to fertile controls. PRL showed a significant prediction of Normozoospermia (AUC=0.836, Z=4.916, p<0.001) in ROC analysis. Data presented here is interesting, requiring further confirmation using larger samples of multiple cohorts.

The current status and future of andrology: A consensus report from the Cairo workshop group

BACKGROUND

In attempting to formulate potential WHO guidelines for the diagnosis of male infertility, the Evidence Synthesis Group noted a paucity of high-quality data on which to base key recommendations. As a result, a number of authors suggested that key areas of research/evidence gaps should be identified, so that appropriate funding and policy actions could be undertaken to help address key questions.

OBJECTIVES

The overall objective of this Consensus workshop was to clarify current knowledge and deficits in clinical laboratory andrology, so that clear paths for future development could be navigated.

MATERIALS AND METHODS

Following a detailed literature review, each author, prior to the face-to-face meeting, prepared a summary of their topic and submitted a PowerPoint presentation. The topics covered were (a) Diagnostic testing in male fertility and infertility, (b) Male fertility/infertility in the modern world, (c) Clinical management of male infertility, and (d) The overuse of ICSI. At the meeting in Cairo on February 18, 2019, the evidence was presented and discussed and a series of consensus points agreed.

RESULTS

The paper presents a background and summary of the evidence relating to these four topics and addresses key points of significance. Following discussion of the evidence, a total of 36 consensus points were agreed.

DISCUSSION

The Discussion section presents areas where there was further debate and key areas that were highlighted during the day.

CONCLUSION

The consensus points provide clear statements of evidence gaps and/or potential future research areas/topics. Appropriate funding streams addressing these can be prioritized and consequently, in the short and medium term, answers provided. By using this strategic approach, andrology can make the rapid progress necessary to address key scientific, clinical, and societal challenges that face our discipline now and in the near future.

Intracytoplasmic sperm injection for male infertility and consequences for offspring

Intracytoplasmic sperm injection (ICSI) has become the most commonly used method of fertilization in assisted reproductive technology. The primary reasons for its popularity stem from its effectiveness, the standardization of the procedure, which means that it can easily be incorporated into the routine practice of fertility centres worldwide, and the fact that it can be used to treat virtually all forms of infertility. ICSI is the clear method of choice for overcoming untreatable severe male factor infertility, but its (over)use in other male and non-male factor infertility scenarios is not evidence-based. Despite all efforts to increase ICSI efficacy and safety through the application of advanced sperm retrieval and cryopreservation techniques, as well as methods for selecting sperm with better chromatin integrity, the overall pregnancy rates from infertile men remain suboptimal. Treating the underlying male infertility factor before ICSI seems to be a promising way to improve ICSI outcomes, but data remain limited. Information regarding the health of ICSI offspring has accumulated over the past 25 years, and there are reasons for concern as risks of congenital malformations, epigenetic disorders, chromosomal abnormalities, subfertility, cancer, delayed psychological and neurological development, and impaired cardiometabolic profile have been observed to be greater in infants born as a result of ICSI than in naturally conceived children. However, as subfertility probably influences the risk estimates, it remains to be determined to what extent the observed adverse outcomes are related to parental factors or associated with ICSI.

Curcumin protects against palmitic acid-induced apoptosis via the inhibition of endoplasmic reticulum stress in testicular Leydig cells

BACKGROUND

Palmitic acid (PA) is a common saturated fatty acid that induces apoptosis in various types of cells, including testicular Leydig cells. There is evidence suggesting that PA is increased in patients with obesity and that PA-induced cell apoptosis may play an important role in obesity-related male infertility. Curcumin, a natural polyphenol, has been reported to exert cytoprotective effects in various cell types. However, the cytoprotective effect of curcumin against PA-induced apoptosis in Leydig cells remains unknown. Therefore, the current study was performed to investigate the protective effects of curcumin in response to PA-induced toxicity and apoptosis in murine Leydig tumor cell line 1 (MLTC-1) cells and explore the mechanism underlying its anti-apoptotic action.

METHODS

MLTC-1 cells were cultured in Roswell Park Institute-1640 medium and divided into five groups. First four groups were treated with 50-400 μM PA, 400 μM PA + 5-40 μM curcumin, 400 μM PA + 500 nM 4-phenylbutyric acid (4-PBA, an endoplasmic reticulum (ER) stress inhibitor), and 500 nM thapsigargin (TG, an ER stress inducer) + 20 μM curcumin, respectively, followed by incubation for 24 h. Effects of PA and/or curcumin on viability, apoptosis, and ER stress in MLTC-1 cells were then determined by cell proliferation assay, flow cytometry, and western blot analysis. The fifth group of MLTC-1 cells was exposed to 400 μM of PA and 5 IU/mL of human chorionic gonadotropin (hCG) for 24 h in the absence and presence of curcumin, followed by measurement of testosterone levels in cell-culture supernatants by enzyme-linked immunosorbent assay (ELISA). Rats fed a high-fat diet (HFD) were treated with or without curcumin for 4 weeks, and the testosterone levels were detected by ELISA.

RESULTS

Exposure to 100-400 μM PA reduced cell viability, activated caspase 3, and enhanced the expression levels of the apoptosis-related protein BCL-2-associated X protein (BAX) and ER stress markers glucose-regulated protein 78 (GRP78) and CCAAT/enhancer binding protein homologous protein (CHOP) in MLTC-1 cells. Treating cells with 500 nM 4-PBA significantly attenuated PA-induced cytotoxicity through inhibition of ER stress. Curcumin (20 μM) significantly suppressed PA- or TG-induced decrease in cell viability, caspase 3 activity, and the expression levels of BAX, CHOP, and GRP78. In addition, treating MLTC-1 cells with 20 μM curcumin effectively restored testosterone levels, which were reduced in response to PA exposure. Similarly, curcumin treatment ameliorated the HFD-induced decrease in serum testosterone level in vivo.

CONCLUSIONS

The present study suggests that PA induces apoptosis via ER stress and curcumin ameliorates PA-induced apoptosis by inhibiting ER stress in MLTC-1 cells. This study suggests the application of curcumin as a potential therapeutic agent for the treatment of obesity-related male infertility.

Decrease in semen quality and Leydig cell function in infertile men: a longitudinal study

STUDY QUESTION

Are infertile men with reduced semen quality at risk of a further decrease in testicular function?

SUMMARY ANSWER

Infertile men with severely reduced semen quality risk further deterioration of semen quality 15 years after treatment for infertility, and a lower baseline sperm concentration was associated with a more pronounced increase in LH and decrease in testosterone/LH ratio at follow-up.

WHAT IS KNOWN ALREADY

Male factors account for up to 50% of human infertility. The most common finding is spermatogenic failure (SgF) yet the life course of semen quality and testosterone production in such men has not been described.

STUDY DESIGN, SIZE, DURATION

A follow-up study of men with SgF was performed 15 years after the initial infertility assessment between January 1995 and December 2000.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Hospital records were used to identify potential participants in the study. A total of 137 men with primary male infertility due to SgF and 70 controls with good semen quality from couples with female factor infertility who attended a tertiary referral centre were included: the participation rate was 31% and 26%, respectively. The men provided semen samples and underwent a physical examination. Blood samples were taken to measure levels of reproductive hormones (FSH, LH, testosterone, sex hormone-binding globulin, estradiol and inhibin B). Current results were compared with results from the initial assessments.

MAIN RESULTS AND THE ROLE OF CHANCE

At the time of follow up the SgF men had significantly lower Leydig cell capacity than the control group as well as much lower semen quality. For the SgF men, between baseline sampling and follow up, the median sperm concentration decreased from 1.9 to 0.6 mill/ml and total sperm count from 7.7 to 2.0 million (P = 0.019 and 0.012, respectively), and 10% developed azoospermia. Calculated free testosterone (cFT), but not total testosterone (tT) decreased in the SgF group by ~0.6% (95% CI 0.1-1.2%) per year. In the SgF group, LH increased by 1.6% (CI 0.9-2.3%) annually, and consequently tT/LH and cFT/LH ratios had decreased by 1.3% (CI 0.5-2.1) and 2.1% (CI 1.2-3.0%), respectively. The increase in LH and the decreases in tT/LH and cFT/LH ratios were more pronounced in men with lower baseline sperm concentrations.

LIMITATIONS, REASONS FOR CAUTION

We consider the case group as representative of infertile men not in need of testosterone treatment at baseline investigation, but do not have information on those that chose not to participate in the follow-up study. There were alterations in some hormone analysis methods during the follow-up period that may introduce uncertainty in interpretation of long-term changes in hormone levels despite rigorous quality control. The validity of the control group suffers from a lack of hormone values at baseline. Also, at follow-up, for practical reasons only one semen sample could be obtained, which makes the effect estimate more uncertain and there is a risk of non-differential misclassification.

WIDER IMPLICATIONS OF THE FINDINGS

Without being able to predict individual outcomes, it is prudent to consider sperm cryopreservation or advise not to postpone fertility treatment when men present with infertility due to impaired semen quality. Whether partly compensated Leydig cell insufficiency in men with SgF will eventually develop into overt testosterone deficiency cannot be determined from our study.

STUDY FUNDING/COMPETING INTEREST(s)

Aase and Einar Danielsen (Grant no. 10-001053), Nordic Research Committee (Grant no. 5109), The Kirsten and Freddie Johansen Fund, and Rigshospitalet's Research Fund (grant no. R24-A812). There are no competing interests.

The relationships between urinary phthalate metabolites, reproductive hormones and semen parameters in men attending in vitro fertilization clinic

Evidence from previous studies has shown that phthalates may play a role in male reproductive function; however, results are still inconclusive, and the mechanism remains unclear. In this study, we first assessed whether exposure to phthalates is associated with altered reproductive hormones and semen parameters in 599 men attending an in vitro fertilization clinic. Secondly, we evaluated whether reproductive hormones could play a mediating role in the association between phthalates and sperm parameters. Eight phthalate metabolites were measured in two different spot urine samples: mono‑n‑butyl phthalate, mono-isobutyl phthalate (MiBP), monoethyl phthalate (MEP), monobenzyl phthalate, and four oxidative metabolites of di‑(2‑ethylhexyl) phthalate (DEHP) [i.e., mono‑(2‑ethylhexyl) phthalate (MEHP), mono‑(2‑ethyl‑5‑hydroxyhexyl) phthalate (MEHHP), mono‑(2‑ethyl‑5‑oxohexyl) phthalate (MEOHP), and mono‑(2‑ethyl‑5‑carboxypentyl) phthalate (MECPP)]. Semen parameters (concentration, volume, motility, and morphology) and reproductive hormones, i.e., follicle-stimulating hormone (FSH), luteinizing hormone (LH), thyroid-stimulating hormone, estradiol (E₂), testosterone (TEST) and prolactin (PROL) were also determined and considered the main study outcomes. Separate multivariate linear regression was used to assess associations between levels of each urinary phthalate metabolite, molar sum of DEHP metabolites (∑DEHP), percentage of MEHP to ∑DEHP (%MEHP), and each outcome (natural log-transformed). Inverse associations were observed between TEST and MiBP (β = -0.099), FSH and MEHHP (β = -0.087), and PROL and MEOHP (β = -0.102), while a positive relationship was seen between E₂ and MEP (β = 0.098). %MEHP was associated positively with FSH (β = 0.118) and LH (β = 0.099), but negatively with TEST/LH (β = -0.086) and TEST/E₂ (β = -0.109). Sperm concentration was associated positively with MECPP (β = 0.131), MEHHP (β = 0.117), MEOHP (β = 0.107) and ∑DEHP (β = 0.111), but negatively with %MEHP (β = -0.135). All p-values were <0.05. Sobel's test indicated that FSH mediated significantly up to 60% of the positive relationship between sperm concentration and MEHHP, while FSH and LH mediated respectively 15 and 12% of the inverse association between sperm concentration and %MEHP. Further research on this topic is warranted.

Risk factors affecting post-pubertal high serum follicle-stimulating hormone in patients with hypospadias

Purpose

The factors affecting spermatogenesis in adulthood in patients with hypospadias (HS) are not clearly understood. In the present study, risk factors affecting post-pubertal high serum follicle-stimulating hormone (FSH) were evaluated in patients with HS.

Materials and methods

Among those with a history of HS surgery, patients in whom endocrinological evaluation regarding pituitary–gonadal axis was performed at 15 years of age or older between March 2004 and April 2018 were enrolled in the present study. High serum FSH was defined as greater than 10 mIU/ml. The severity of HS was divided into mild and severe. Factors affecting the post-pubertal high serum FSH were estimated.

Results

Seventy-nine patients were included in the present study. The severity of HS was mild in 35 and severe in 44. History of undescended testis (UDT) was confirmed in 12. High serum FSH was detected in nine. On logistic regression model analysis, a history of UDT was the only significant factor for high serum FSH. The incidence of high serum FSH in patients with UDT was significantly higher than that in those without UDT (58.3% vs 7.5%, p < 0.01). When stratified by severity of HS and the presence of UDT, high serum FSH was detected in 70% in patients with severe HS and UDT, whereas less than 10% in other groups.

Conclusions

A history of UDT was a significant factor for post-pubertal high serum FSH in patients with HS. Accordingly, the presence of UDT may be a marker for impaired spermatogenesis in patients with HS, especially in severe cases.

Single-dose prednisolone alters endocrine and haematologic responses and exercise performance in men

The aim of this study was to investigate the effect of a single dose of prednisolone on (A) high-intensity interval cycling performance and (B) post-exercise metabolic, hormonal and haematological responses. Nine young men participated in this double-blind, randomised, cross-over study. The participants completed exercise sessions (4 × 4 min cycling bouts at 90-95% of peak heart rate), 12 h after ingesting prednisolone (20 mg) or placebo. Work load was adjusted to maintain the same relative heart rate between the sessions. Exercise performance was measured as total work performed. Blood samples were taken at rest, immediately post exercise and up to 3 h post exercise. Prednisolone ingestion decreased total work performed by 5% (P < 0.05). Baseline blood glucose was elevated following prednisolone compared to placebo (P < 0.001). Three hours post exercise, blood glucose in the prednisolone trial was reduced to a level equivalent to the baseline concentration in the placebo trial (P > 0.05). Prednisolone suppressed the increase in blood lactate immediately post exercise (P < 0.05). Total white blood cell count was elevated at all time-points with prednisolone (P < 0.01). Androgens and sex hormone-binding globulin were elevated immediately after exercise, irrespective of prednisolone or placebo. In contrast, prednisolone significantly reduced the ratio of testosterone/luteinizing hormone (P < 0.01). Acute prednisolone treatment impairs high-intensity interval cycling performance and alters metabolic and haematological parameters in healthy young men. Exercise may be an effective tool to minimise the effect of prednisolone on blood glucose levels.

Hypogonadism and Cryptorchidism

Congenital cryptorchidism (undescended testis) is one of the most common congenital urogenital malformations in boys. Prevalence of cryptorchidism at birth among boys born with normal birth weight ranges from 1.8 to 8.4%. Cryptorchidism is associated with a risk of low semen quality and an increased risk of testicular germ cell tumors. Testicular hormones, androgens and insulin-like peptide 3 (INSL3), have an essential role in the process of testicular descent from intra-abdominal position into the scrotum in fetal life. This explains the increased prevalence of cryptorchidism among boys with diseases or syndromes associated with congenitally decreased secretion or action of androgens, such as patients with congenital hypogonadism and partial androgen insensitivity syndrome. There is evidence to support that cryptorchidism is associated with decreased testicular hormone production later in life. It has been shown that cryptorchidism impairs long-term Sertoli cell function, but may also affect Leydig cells. Germ cell loss taking place in the cryptorchid testis is proportional to the duration of the condition, and therefore early orchiopexy to bring the testis into the scrotum is the standard treatment. However, the evidence for benefits of early orchiopexy for testicular endocrine function is controversial. The hormonal treatments using human chorionic gonadotropin (hCG) or gonadotropin-releasing hormone (GnRH) to induce testicular descent have low success rates, and therefore they are not recommended by the current guidelines for management of cryptorchidism. However, more research is needed to assess the effects of hormonal treatments during infancy on future male reproductive health.

Anogenital distance is associated with semen quality but not reproductive hormones in 1106 young men from the general population

STUDY QUESTION

Is anogenital distance (AGD) associated with semen quality and reproductive hormones in men from the general population?

SUMMARY ANSWER

Short AGD measured from the anus to the base of scrotum (AGDAS) was associated with reduced sperm counts and morphology but not with sperm motility or reproductive hormones.

WHAT IS KNOWN ALREADY

AGD is longer in males than in females. In rodents, AGD is a well-established and sensitive marker of disruption during the masculinization programming window in utero and it has been suggested to be so in humans as well. Therefore, the average AGD would be expected to be shorter in men with poor semen quality, which some studies have confirmed while others have not.

STUDY DESIGN, SIZE, DURATION

This cross-sectional population-based study was of 1106 men included between 2012 and 2016.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Men from the general Danish population (median age 19 years), unselected with regard to fertility status and semen quality, delivered a semen sample, had a blood sample drawn, which was analyzed for concentrations of reproductive hormones, and answered a comprehensive questionnaire. They also had a physical examination performed including determination of AGD measured as the distance between anus and scrotum (AGDAS) and penis (AGDAP). Odds ratios (OR) and 95% CI were estimated for a man having abnormal semen parameters according to the World Health Organization's reference values or a low/high concentration of reproductive hormones (defined as the lowest or highest 10%) depending on AGD. AGD was categorized in four strata: ≤10th percentile, 10th-30th percentile, 30th-50th percentile and >50th percentile.

MAIN RESULTS AND THE ROLE OF CHANCE

Men with the 10% shortest AGDAS had a more than doubled risk (OR: 2.19, 95% CI: 1.40-3.42) of being in the subfertile range for either sperm concentration (<15 million/mL) or sperm morphology (<4%) compared to men with AGDAS above the median (reference). Men in the 10th-30th percentile also had an increased OR of 1.48 (95% CI: 1.06-2.08) but not men in the 30th-50th percentile (OR: 1.14, 95% CI: 0.81-1.62). AGDAP was only weakly related to semen quality. AGD was not associated with testicular volume or any of the reproductive hormones.

LIMITATIONS, REASONS FOR CAUTION

Limitations include the potential non-differential misclassification of reproductive outcomes based on a single semen and blood sample and some between-examiner differences in AGD measurements which introduces noise and may result in an underestimation of observed associations.

WIDER IMPLICATIONS OF THE FINDINGS

Our study of men from the general population confirmed associations between AGD and semen quality, supporting the hypothesis that AGD in humans could be a marker of fetal testicular development. This suggests that the low semen quality in Danish men may partly be explained by prenatal factors.

STUDY FUNDING/COMPETING INTEREST(S)

The study has received financial support from the ReproUnion (L.P.); the Research fund of Rigshospitalet, Copenhagen University Hospital (N.J.); Grants R01ES016863-04 and R01ES016863-02S4; National Institute of Environmental Health Sciences (NIEHS) and National Institute of Environmental Health Sciences grant (P30ES023515) (S.S.); the European Union (Contract numbers BMH4-CT96-0314, QLK4-CT-1999-01422, QLK4-CT-2002-00603, FP7/2007-2013, DEER Grant agreement no. 212844); the Danish Ministry of Health; the Danish Environmental Protection Agency; A.P. Møller and wife Chastine McKinney Møllers foundation; and Svend Andersens Foundation. None of the funders had any role in the study design, collection, analysis or interpretation of data, writing of the paper or publication decisions. The authors have nothing to declare.

TRIAL REGISTRATION NUMBER

N/A.