The genetic causes of male factor infertility: a review

Male infertility and perfluoroalkyl and poly-fluoroalkyl substances: evidence for alterations in phosphorylation of proteins and fertility-related functional attributes in bull spermatozoa†

BACKGROUND

Perfluoroalkyl and poly-fluoroalkyl substances (PFAS) are pervasive environmental pollutants and potential threats to reproductive health. Epidemiological studies have established an association between PFAS and male infertility, but the underlying mechanisms are unclear.

OBJECTIVES

Investigate the effect of perfluorooctane sulfonic acid (PFOS), the most prevalent and representative PFAS, on bull sperm protein phosphorylation and function.

METHODS

We exposed bull sperm to PFOS at 10 (average population exposure) and 100 μM (high-exposure scenario), and analyzed global proteomic and phosphoproteomic analysis by TMT labeling and Nano LC-MS/MS. We also measured sperm fertility functions by flow cytometry.

RESULTS

PFOS at 10-μM altered sperm proteins linked to spermatogenesis and chromatin condensation, while at 100 μM, PFOS affected proteins associated with motility and fertility. We detected 299 phosphopeptides from 116 proteins, with 45 exhibiting differential expression between control and PFOS groups. PFOS dysregulated phosphorylation of key proteins (ACRBP, PRKAR2A, RAB2B, SPAG8, TUBB4B, ZPBP, and C2CD6) involved in sperm capacitation, acrosome reaction, sperm-egg interaction, and fertilization. PFOS also affected phosphorylation of other proteins (AQP7, HSBP9, IL4I1, PRKAR1A, and CCT8L2) related to sperm stress resistance and cryotolerance. Notably, four proteins (PRM1, ACRBP, TSSK1B, and CFAP45) exhibited differential regulation at both proteomic and phosphoproteomic levels. Flow cytometric analysis confirmed that PFOS increased protein phosphorylation in sperm and also decreased sperm motility, viability, calcium, and mitochondrial membrane potential and increased mitochondrial ROS in a dose-dependent manner.

CONCLUSIONS

This study demonstrates that PFOS exposure negatively affects phosphorylation of proteins vital for bull sperm function and fertilization.

Correlation of MTHFR C677T Polymorphism with Male Infertility among Indian Population: Case-Control Study

This case-control study investigated the correlation between male infertility in India and the methylenetetrahydrofolate reductase (MTHFR) C677T variant. Infertile males were utilized as the case group in the study, whereas fertile individuals served as the control group. The C677T polymorphism was genotyped using PCR-RFLP analysis (polymerase chain reaction-restriction fragment length polymorphism). The Chi-square test and odds ratio calculation were implemented in the statistical analysis method for assessing the correlation between the C677T mutation and infertility. The results of this study revealed that the case group (9.4%) had a substantially greater prevalence of the C677T variation than the control group (1.6%). The C677T variation is significantly associated with male infertility by the Chi-square test (P value: 0.006). According to these results, the MTHFR gene›s C677T variation may increase the incidence of male infertility in the Indian population. Additional evaluations were also conducted to investigate the association between the C677T variation and particular infertility indicators. The C677T variation has been demonstrated to have been significantly correlated with a low or missing sperm count (p 0.05). These findings highlight the potential function of the MTHFR gene in reproductive health and advance our understanding of the genetic underpinnings of male infertility. It is encouraged to investigate the underlying mechanisms and additional investigation of the underlying mechanisms and to support the creation of individualized approaches to diagnosing and managing male infertility.

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

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

IAS-FET: An intelligent assistant system and an online platform for enhancing successful rate of in-vitro fertilization embryo transfer technology based on clinical features

BACKGROUND

Among all of the assisted reproductive technology (ART) methods, in vitro fertilization-embryo transfer (IVF-ET) holds a prominent position as a key solution for overcoming infertility. However, its success rate hovers at a modest 30% to 70%. Adding to the challenge is the absence of effective models and clinical tools capable of predicting the outcome of IVF-ET before embryo formation. Our study is dedicated to filling this critical gap by aiming to predict IVF-ET outcomes and ultimately enhance the success rate of this transformative procedure.

METHODS

In this retrospective study, infertile patients who received artificial assisted pregnancy treatment at Gansu Provincial Maternity and Child-care Hospital in China were enrolled from 2016 to 2020. Individual's clinical information were studied by cascade XGBoost method to build an intelligent assisted system for predicting the outcome of IVF-ET, called IAS-FET. The cascade XGBoost model was trained using clinical information from 2292 couples and externally tested using clinical information from 573 couples. In addition, several schemes which will be of help for patients to adjust their physical condition to improve their success rate on ART were suggested by IAS-FET.

RESULTS

The outcome of IVF-ET can be predicted by the built IAS-FET method with the area under curve (AUC) value of 0.8759 on the external test set. Besides, this IAS-FET method can provide several schemes to improve the successful rate of IVF-ET outcomes. The built tool for IAS-FET is addressed as a free platform online at http://www.cppdd.cn/ART for the convenient usage of users.

CONCLUSIONS

It suggested the significant influence of personal clinical features for the success of ART. The proposed system IAS-FET based on the top 27 factors could be a promising tool to predict the outcome of ART and propose a plan for the patient's physical adjustment. With the help of IAS-FET, patients can take informed steps towards increasing their chances of a successful outcome on their journey to parenthood.

Identification of potential key genes related to idiopathic male infertility using RNA-sequencing data: an in-silico approach

Among reproductive health problems, idiopathic infertility affects married couples. The current diagnosis of male infertility focuses on the concentration, motility, and morphology of sperm in the ejaculate. Since the molecular mechanism of idiopathic infertility is unknown, identification of Differentially Expressed Genes (DEGs) among the control and idiopathic infertile male can shed light on diagnosis and treatment. Here, we analyzed the dataset GSE65683 to identify DEGs in idiopathic human sperm in three groups of patients: (i) Timed Intercourse (TIC); (ii) Intrauterine Insemination (IUI); and (iii) Assisted Reproductive Technology (ART). The enrichment analysis was carried out using DAVID (Database for Annotation, Visualization and Integrated Discovery) and GeneCodis for the DEGs. Protein-Protein Interaction (PPI) network of these DEGs were constructed using the STRING database. The network parameters such as degree and betweenness were calculated to select the important hubs. In total, 118 DEGs in TIC, 446 in IUI, and 188 in ART were identified. PPI network was constructed and identified critical top hub genes such as ACTB, BTBD6, EIF2S3, EIF3A, EIF4E, POLR2L, RPL4, RPL7, RPS11, RPL13, RPS15, RPL23, RPL27, RPL9, RPLP0 and UBA52 that may play an essential role in idiopathic male infertility. Thus, the identified hub genes may provide an insight into the molecular mechanism and contribute to discovering novel therapeutic targets and developing new strategies for idiopathic male infertility.

The effect of sperm DNA fragmentation on ICSI outcomes depending on oocyte quality

BACKGROUND

Sperm deoxyribonucleic acid (DNA) fragmentation is commonly encountered in spermatozoa, and the oocyte assumes responsibility for repairing sperm DNA fragmentation during the oocyte-embryo transition.

OBJECTIVES

This study aimed to investigate whether the effect of sperm DNA fragmentation on intracytoplasmic sperm injection outcomes depends on the incidence of oocyte dimorphisms.

MATERIALS AND METHODS

For the present cohort, 2942 fertilized oocytes from 525 patients submitted to intracytoplasmic sperm injection cycles were assessed. The present study was conducted in a private in vitro fertilization center affiliated to a university from June 2016 to July 2019. Semen samples were divided into the following two groups depending on the sperm DNA fragmentation index: a low fragmentation index group (<30% sperm DNA fragmentation, n = 1468) and a high fragmentation index group (≥30% sperm DNA fragmentation, n = 486). In addition, mature oocytes were examined before sperm injection, and intracytoplasmic and extracytoplasmic defects were recorded. The effect of the sperm DNA fragmentation index on laboratory and clinical intracytoplasmic sperm injection outcomes (depending on the presence of oocyte defects) was evaluated.

RESULTS

Significant increases in the rates of fertilization, high-quality embryo, implantation, and pregnancy were noted for cycles with <30% sperm DNA fragmentation than cycles with ≥30% sperm DNA fragmentation (regardless of the presence of oocyte dimorphisms). The presence of dimorphisms significantly impacted laboratory and clinical outcomes. The lowest fertilization and high-quality embryo rates were observed when a high sperm DNA fragmentation index was associated with the presence of dark cytoplasm, vacuoles, resistant membrane, and non-resistant membrane. The lowest implantation and pregnancy rates were observed when a high sperm DNA fragmentation index was associated with the presence of vacuoles, defective perivitelline space, and fragmented polar body. The effect of sperm DNA fragmentation on miscarriage rates was significantly influenced by the presence of centrally located cytoplasmic granulation, a defective perivitelline space and non-resistant membrane.

CONCLUSION

A high sperm DNA fragmentation index increases the likelihood of miscarriage in intracytoplasmic sperm injection cycles, an effect that may potentially be magnified by the presence of oocyte dysmorphisms.

The human sperm proteome-Toward a panel for male fertility testing

BACKGROUND

Although male factor accounts for 40%-50% of unintended childlessness, we are far from fully understanding the detailed causes. Usually, affected men cannot even be provided with a molecular diagnosis.

OBJECTIVES

We aimed at a higher resolution of the human sperm proteome for better understanding of the molecular causes of male infertility. We were particularly interested in why reduced sperm count decreases fertility despite many normal-looking spermatozoa and which proteins might be involved.

MATERIAL AND METHODS

Applying mass spectrometry analysis, we qualitatively and quantitatively examined the proteomic profiles of spermatozoa from 76 men differing in fertility. Infertile men had abnormal semen parameters and were involuntarily childless. Fertile subjects exhibited normozoospermia and had fathered children without medical assistance.

RESULTS

We discovered proteins from about 7000 coding genes in the human sperm proteome. These were mainly known for involvements in cellular motility, response to stimuli, adhesion, and reproduction. Numbers of sperm proteins showing at least threefold deviating abundances increased from oligozoospermia (N = 153) and oligoasthenozoospermia (N = 154) to oligoasthenoteratozoospermia (N = 368). Deregulated sperm proteins primarily engaged in flagellar assembly and sperm motility, fertilization, and male gametogenesis. Most of these participated in a larger network of male infertility genes and proteins.

DISCUSSION

We expose 31 sperm proteins displaying deviant abundances under infertility, which already were known before to have fertility relevance, including ACTL9, CCIN, CFAP47, CFAP65, CFAP251 (WDR66), DNAH1, and SPEM1. We propose 18 additional sperm proteins with at least eightfold differential abundance for further testing of their diagnostic potential, such as C2orf16, CYLC1, SPATA31E1, SPATA31D1, SPATA48, EFHB (CFAP21), and FAM161A.

CONCLUSION

Our results shed light on the molecular background of the dysfunctionality of the fewer spermatozoa produced in oligozoospermia and syndromes including it. The male infertility network presented may prove useful in further elucidating the molecular mechanism of male infertility.

Phytochemicals: Alternative for Infertility Treatment and Associated Conditions

Infertility and obstetric complications have become global health issues in the past few years. Infertility is defined as the inability of a couple to conceive even after twelve months or more of regular and unprotected intercourse. According to WHO data published in the year 2020, 186 million people have infertility globally. Factors leading to infertility are variable in both males and females. But some common factors include smoking, alcohol consumption, obesity, and stress. Various synthetic drugs and treatment options are available that are effective in treating infertility, but their prolonged usage produces various unwanted adverse effects like hot flashes, mood swings, headaches, and weight gain. In extreme cases, these may also lead to the development of anxiety and depression. Herbal remedies have gained a lot of popularity over the years, and people's inclination toward them has increased all over the world. The prime reason is that these show significant therapeutic efficacy and have fewer side effects. The therapeutic efficacy of plants can be attributed to the presence of diverse phytochemical classes of constituents like alkaloids, flavonoids, and volatile oils. These secondary metabolites, or phytomolecules, can be used to develop herbal formulations. The review highlights the applications and mechanisms of action of various phytochemicals for treating infertility. Also, it focuses on the various future prospects associated with it.

Zbtb40 Deficiency Leads to Morphological and Phenotypic Abnormalities of Spermatocytes and Spermatozoa and Causes Male Infertility

Studies on the gene regulation of spermatogenesis are of unusual significance for maintaining male reproduction and treating male infertility. Here, we have demonstrated, for the first time, that a loss of ZBTB40 function leads to abnormalities in the morphological and phenotypic characteristics of mouse spermatocytes and spermatids as well as male infertility. We revealed that Zbtb40 was expressed in spermatocytes of mouse testes, and it was co-localized with γH2AX in mouse secondary spermatocytes. Interestingly, spermatocytes of Zbtb40 knockout mice had longer telomeres, compromised double-strand break (DSB) repair in the sex chromosome, and a higher apoptosis ratio compared to wild-type (WT) mice. The testis weight, testicular volume, and cauda epididymis body weight of the Zbtb40^+/- male mice were significantly lower than in WT mice. Mating tests indicated that Zbtb40^+/- male mice were able to mate normally, but they failed to produce any pups. Notably, sperm of Zbtb40^+/- mice showed flagellum deformities and abnormal acrosome biogenesis. Furthermore, a ZBTB40 mutation was associated with non-obstructive azoospermia. Our results implicate that ZBTB40 deficiency leads to morphological and phenotypic abnormalities of spermatocytes and spermatids and causes male infertility. This study thus offers a new genetic mechanism regulating mammalian spermatogenesis and provides a novel target for gene therapy in male infertility.

Polymorphic Rearrangements of Human Chromosome 9 and Male Infertility: New Evidence and Impact on Spermatogenesis

Chromosomal polymorphisms are structural variations in chromosomes that define the genomic variance of a species. These alterations are recurrent in the general population, and some of them appear to be more recurrent in the infertile population. Human chromosome 9 is highly heteromorphic, and how its rearrangement affects male fertility remains to be fully investigated. In this study, we aimed to investigate the association between the polymorphic rearrangements of chromosome 9 and male infertility via an Italian cohort of male infertile patients. Cytogenetic analysis was carried out, along with Y microdeletion screening, semen analysis, fluorescence in situ hybridization, and TUNEL assays using spermatic cells. Chromosome 9 rearrangements were observed in six patients: three of them showed a pericentric inversion, while the others showed a polymorphic heterochromatin variant 9qh. Of these, four patients exhibited oligozoospermia associated with teratozoospermia, along with a percentage of aneuploidy in the sperm of above 9%, in particular, an increase in XY disomy. Additionally, high values for sperm DNA fragmentation (≥30%) were observed in two patients. None of them had microdeletions to the AZF loci on chromosome Y. Our results suggest that polymorphic rearrangements of chromosome 9 might be associated with abnormalities in sperm quality due to incorrect spermatogenesis regulation.

Towards a Multi-Omics of Male Infertility

Infertility is a common problem affecting one in six couples and in 30% of infertile couples, the male factor is a major cause. A large number of genes are involved in spermatogenesis and a significant proportion of male infertility phenotypes are of genetic origin. Studies on infertility have so far primarily focused on chromosomal abnormalities and sequence variants in protein-coding genes and have identified a large number of disease-associated genes. However, it has been shown that a multitude of factors across various omics levels also contribute to infertility phenotypes. The complexity of male infertility has led to the understanding that an integrated, multi-omics analysis may be optimal for unravelling this disease. While there is a vast array of different factors across omics levels associated with infertility, the present review focuses on known factors from the genomics, epigenomics, transcriptomics, proteomics, metabolomics, glycomics, lipidomics, miRNomics, and integrated omics levels. These include: repeat expansions in AR, POLG, ATXN1, DMPK, and SHBG, multiple SNPs, copy number variants in the AZF region, disregulated miRNAs, altered H3K9 methylation, differential MTHFR, MEG3, PEG1, and LIT1 methylation, altered protamine ratios and protein hypo/hyperphosphorylation. This integrative review presents a step towards a multi-omics approach to understanding the complex etiology of male infertility. Currently only a few genetic factors, namely chromosomal abnormalities and Y chromosome microdeletions, are routinely tested in infertile men undergoing intracytoplasmic sperm injection. A multi-omics approach to understanding infertility phenotypes may yield a more holistic view of the disease and contribute to the development of improved screening methods and treatment options. Therefore, beside discovering as of yet unknown genetic causes of infertility, integrating multiple fields of study could yield valuable contributions to the understanding of disease development. Future multi-omics studies will enable to synthesise fragmented information and facilitate biomarker discovery and treatments in male infertility.

ATP5D Is a Potential Biomarker for Male Fertility

Background

Infertility is a global medical and social problem that affects human health and social development. At present, about 15% of couples of the right age in the world are infertile. As all we know, genetic defects are the most likely underlying cause of the pathology. ATP5D is also known as the delta subunit of mitochondrial ATP synthase. Mitochondria maintain sperm vitality, capacitation, acrosome reaction, and DNA integrity through ATP. Mitochondrial damage can trigger energy synthesis disorders, resulting in decreased sperm quality and function or even disappearance. The specific role of ATP5D in regulation of the male reproductive system remains elusive.

Methods

In this study, semen from normal and infertile males were collected and their indicators were examined by analysis of routine sperm parameters; ATP5D protein content in semen was examined by ELISA. Singer sequencing was used to detect whether there was a mutated of ATP5D in semen. Meanwhile, ATP5D knockout (KO) and knockin (KI) male mice were selected at 8-12 weeks of age and mated with adult wild-type (WT) female mice for more than two months to assess their fertility and reproductive ability. Morphological changes in tissues such as testes and epididymis were observed by HE staining; spermatozoa were taken from the epididymis of the mice; sperm counts were performed and morphological changes were observed by Diff-Quik staining.

Results

The results showed that the expression of ATP5D in infertile males was significantly lower than that in normal males (P < 0.001) and the normal morphology rate of spermatozoa was much lower than that of normal males, and the sequencing results showed no mutations. The animal reproductive experiments showed no significant changes in the number of fertility in KO/KI mice compared with WT mice, but the duration of fertility was significantly longer (P = 0.02). The testicular cells in KO mice were loosely arranged and disorganized, the lumen was larger, the interstitial cells were atrophied, and the number of spermatozoa was reduced and the malformation rate was higher in WT males. This suggests that ATP5D is an essential protein for sperm formation and fertility in male mice and may be used as a biomarker of male fertility.

Conclusion

This study found ATP5D correlated with male infertility and the expression levels were significantly reduced in the seminal plasma of all male infertile patients without gene mutations. KO male significantly prolonged fertility time and impaired testicular histomorphology. This suggests that ATP5D may be associated with spermatogenic function and fertility in male mice and may be used as a biomarker for male fertility. Future studies are required to elucidate the potential mechanisms. The trial registration number is KLL-2021-266.

Semen rheology and its relation to male infertility

Infertility affects 15% of couples of reproductive age worldwide. In spite of many advances in understanding and treating male infertility, there is still a number of issues that need further investigation and translation to the clinic. Here, we review the current knowledge and practice concerning semen rheology and its relation with pathological states affecting male infertility. Although it is well recognized that altered rheological properties of semen can impair normal sperm movement in the female reproductive tract, routine semen analysis is mostly focused on number, motility and morphology of spermatozoa, and includes only an approximate, operator-dependent measure of semen viscosity. The latter is based on the possible formation of a liquid thread from a pipette where a semen sample has been aspirated, a method that is sensitive not only to viscosity but also to elongational properties and surface tension of semen. The formation of a liquid thread is usually associated with a gel-like consistency of the sample and changes in spermatozoa motility in such a complex medium are still to be fully elucidated. The aim of this review is to point out that a more quantitative and reliable characterization of semen rheology is in order to improve the current methods of semen analysis and to develop additional tools for the diagnosis and treatment of male infertility.

Copy number variation of horse Y chromosome genes in normal equine populations and in horses with abnormal sex development and subfertility: relationship of copy number variations with Y haplogroups

Structural rearrangements like copy number variations in the male-specific Y chromosome have been associated with male fertility phenotypes in human and mouse but have been sparsely studied in other mammalian species. Here, we designed digital droplet PCR assays for 7 horse male-specific Y chromosome multicopy genes and SRY and evaluated their absolute copy numbers in 209 normal male horses of 22 breeds, 73 XY horses with disorders of sex development and/or infertility, 5 Przewalski's horses and 2 kulans. This established baseline copy number for these genes in horses. The TSPY gene showed the highest copy number and was the most copy number variable between individuals and breeds. SRY was a single-copy gene in most horses but had 2-3 copies in some indigenous breeds. Since SRY is flanked by 2 copies of RBMY, their copy number variations were interrelated and may lead to SRY-negative XY disorders of sex development. The Przewalski's horse and kulan had 1 copy of SRY and RBMY. TSPY and ETSTY2 showed significant copy number variations between cryptorchid and normal males (P < 0.05). No significant copy number variations were observed in subfertile/infertile males. Notably, copy number of TSPY and ETSTY5 differed between successive male generations and between cloned horses, indicating germline and somatic mechanisms for copy number variations. We observed no correlation between male-specific Y chromosome gene copy number variations and male-specific Y chromosome haplotypes. We conclude that the ampliconic male-specific Y chromosome reference assembly has deficiencies and further studies with an improved male-specific Y chromosome assembly are needed to determine selective constraints over horse male-specific Y chromosome gene copy number and their relation to stallion reproduction and male biology.

Association of DAZL polymorphisms and DAZ deletion with male infertility: a systematic review and meta-analysis

BACKGROUND

Various populations have been investigated for the occurrence of two key DAZL polymorphisms, 260A > G (rs11710967) and 386A > G (rs121918346), as well as complete DAZ cluster deletion, with conflicting results.

OBJECTIVE

The purpose of the current meta-analysis was to investigate if there is an association between DAZL polymorphisms and complete deletion of the DAZ cluster gene with male infertility.

METHODS

Up until September 2022, a thorough search was conducted in the Pubmed and Google scholar databases. For 260A > G polymorphism, 8 studies with 2077 cases and 1398 controls, 13 studies for 386A > G polymorphism (4343 cases and 3727 controls) and 17 studies of DAZ deletion (2820 cases and 1589 controls) were included in the pooled analysis. All of the studies were statistically analysed by Review Manager 5.4, and publication bias was evaluated with JASP 0.16.2.0 software utilising funnel plots and Egger's linear regression test.

RESULTS

The meta analysis result for pooled data indicated no association between 260A > G and 386A > G polymorphisms and male infertility in any of the genetic models or ethnicities. However, there was a definite correlation between complete deletion of the DAZ gene cluster and male infertility, with an OR = 13.23, 95% confidence interval (6.63-26.39), and p < 0.00001. In the stratified analysis by ethnicity, Caucasians and Asian ethnic groups showed the similar relationship.

CONCLUSION

In order to arrive at more definitive conclusions, further study should be conducted, including studies from a larger range of nations and nationalities.

Male factor infertility: A contemporary overview of investigation, diagnosis and management

Infertility, defined as the failure to achieve a clinical pregnancy after 1 year of regular, unprotected sexual intercourse, is a public health issue of global concern. It affects up to 12% of couples worldwide. While traditionally, research and treatment have focused on female causes of infertility, male factors contribute to up to 70% of cases and therefore deserve appropriate recognition. The purpose of this comprehensive review is to detail the diagnostic work-up, investigations and management of male factor infertility. We discuss much-debated pathologies, such as varicocele, and novel investigations, including sperm DNA fragmentation and reactive oxygen species.

Level of evidence: Not applicable

Molecular mechanism behind methamphetamine-induced damages in testicular tissue: Evidences for oxidative stress, autophagy, and apoptosis

Methamphetamine (METH) is shown to cause massive oxidative stress and apoptosis in testicular tissue. This study attempted to investigate the possible effects of METH chronic administration on the crosstalk between oxidative DNA damage (ODD), the ODD repairing process, autophagy, and apoptosis in testicular tissue. For this purpose, 20 rats were divided into control and METH (2.5 mg/kg)-received groups (N = 10 rats/group). Following 7 days, the tubular differentiation (TDI) and spermiogenesis (SPI) indices, histomorphometric alterations, intracytoplasmic carbohydrate and lipid storage in germ and Sertoli cells along with expression levels of proliferating cell nuclear antigen (PCNA), as a key element in regulating base excision repair (BER) enzymes expression/activity were assessed. Moreover, the expression levels of uracil-DNA (UDG) and methylpurine (MPG) DNA glycosylases and microtubule-associated protein light chain 3 (LC3-I/II), and apoptotic cells distribution in testicular tissue were evaluated. Observations revealed that METH significantly suppressed spermatogenesis and spermiogenesis development, altered intracytoplasmic carbohydrate and lipid storage, increased ODD, and suppressed the PCNA expression compared to the control group (p < 0.05). Furthermore, METH-received animals exhibited a remarkable (p < 0.05) reduction in UDG and MPG, increment in LC3-I/II expressions, and apoptotic cells distribution. In conclusion, METH consumption results in a failed intracytoplasmic glucose storage (primary metabolites of Sertoli and germ cells) and oxidative stress (OS) circumstance in the testicular tissue. Further, METH can induce ODD by suppressing the expression levels of PCNA and BER enzymes, UDG and MPG. Finally, we demonstrated that METH-induced massive ODD is capable of initiating autophagy signalling that leads to progressive apoptosis in the testicular tissue.

MicroRNA expression in male infertility

Male infertility is a multifactorial disorder that involves different physiopathological mechanisms and multiple genes. In this sense, we analyse the role of miRNAs in this pathology. Gene expression analysis can provide relevant information to detect biomarkers, signalling pathways, pathologic mechanisms, and potential therapeutic targets for the disease. In this review, we describe four miRNA microarrays related to patients who present infertility diseases, including azoospermia, asthenozoospermia, and oligoasthenozoospermic. We selected 13 miRNAs with altered expressions in testis tissue (hsa-miR-122-5p, hsa-miR-145-5p, hsa-miR-16-5p, hsa-miR-193a-3p, hsa-miR-19a-3p, hsa-miR-23a-3p, hsa-miR-30b-5p, hsa-miR-34b-5p, hsa-miR-34c-5p, hsa-miR-374b-5p, hsa-miR-449a, hsa-miR-574-3p and hsa-miR-92a-3p), and systematically examine the mechanisms of four relevant miRNAs (hsa-miR-16-5p, hsa-miR-19a-3p, hsa-miR-92a-3p and hsa-miR-30b-5p) which we found that regulated a large number of proteins. An interaction network was generated, and its connections allowed us to identify signalling pathways and interactions between proteins associated with male infertility. In this way, we confirm that the most affected and relevant pathway is the PI3K-Akt signalling.

Male infertility and the impact of lifestyle in the Greek population: A case-control study

Background and Aims

Collection of epidemiological data has become a crucial step in every fertility evaluation, especially regarding idiopathic male infertility. Information on data such as tobacco smoking, alcohol intake, and body mass index can provide crucial information regarding the dynamics between fertility status and everyday practices. We aim to set the base for epidemiological studies on male infertility in the Greek population.

Methods

Four hundred and fourteen Greek volunteers were asked to fill in a questionnaire regarding their characteristics and lifestyle preferences, followed by a seminogram. Depending on their answers, they were divided into groups and data were analyzed for correlation with seminogram parameters using Spearman's rank correlation test.

Results

Our results indicate that a high body mass index (BMI) is negatively correlated with all three seminogram parameters (number, motility, and morphology) and exposure to radiation or chemicals is negatively correlated with sperm motility, with a p < 0.01.

Conclusions

These findings indicate negative correlations of BMI and exposure to radiation/chemicals with semen parameters in the Greek population. Such information can be used to plan a diagnostic approach or even therapeutic interventions.

Potential clinical value of in vitro spermatogenesis

Infertility has become the third most common disease threatening human health, immediately after tumors and cardiovascular diseases. Male infertility is primarily caused by spermatogenesis disorders which may be classified as either genetic or non-genetic. For part of non-genetic disorders, in vitro spermatogenesis can be induced by adjusting the microenvironment of the testis culture. Establishing the in vitro spermatogenic induction system helps to clarify the critical molecular mechanisms in spermatogonia self-renewal, spermatocyte meiosis, and sperm formation during spermatogenesis. In this review, we summarize recent advances in the field of in vitro sperm cells induction. Therefore, we hope to provide ideas and solutions for the clinical treatment of male infertility.

Association of methyltetrahydrofolate reductase gene mutation, homocysteine level with semen quality of Iraqi infertile males

Background

Infertility is very common condition and almost 50% of cases are due to male factors. Several genetic and environmental factors are responsible for the poor quality and reduced number of sperms in several cases of infertility. The present study was designed to investigate the association between semen parameters, homocysteine, and the risk of C677T polymorphism of MTHFR gene in infertile males of Iraqi population.

Methods

This Case–control study has been conducted from February 2019 to July 2021 at a molecular laboratory in the Anatomy and Histology Department/college of Medicine/University of Kufa/Najaf/Iraq. It was composed of 353 infertile male patients. They were divided into five groups: 90 azoospermic, 84 oligospermia, 64 asthenospermic, 50 oligoasthenospermic, and 65 teratospermic with an age range 20–46 years compared with 100 fertile males as control with age range 21–49 years. In order to detect homocysteine levels, we used Hcy ELISA Kit. C677T mutation of MTHFR gene was employed by PCR–RFLP technique.

Results

Our data revealed three genotypes of MTHFR C677T, 167 (47.3%) subjects had CC genotype, 116 (32.9%) subjects had CT genotype and 70 (21.1%) subjects had TT genotype. Furthermore, T allele was associated with higher risk of infertility in all patients groups for any genetic model. In total infertile subjects (codominant model: CT vs. CC, OR = 2.0, 95% C.I = 1.2–3.3, P = 0.011; TT vs. CC, OR = 4.8, 95% C.I = 3.3–8.2, P = 0.0003; dominant model: CT + TT vs. CC, OR = 2.8, 95% C.I = 1.7–4.5, P = 0.0001). Oligoasthenospermic patients associated with higher risk in CT heterozygous genotype (OR = 2.8, 95% C.I = 1.0–4.9, P = 0.03) and TT homozygous of mutant allele (OR = 6.3, 95% C.I = 1.9–9.2, P = 0.002). Homocystein level was elevated in all infertile groups when compared with control group (P < 0.01), but the elevation was marked in oligoasthenospermia group. As well as, the level of Serum Hcy exhibited the highest value in TT mutant genotype (39.7 µmol/ml) followed by CT genotype (28.5 µmol/ml) while the lowest level of Hcy recorded in CC genotype (14.6 µmol/ml) for oligoasthenospermia group.

Conclusions

By relating the MTHFR C677T gene mutation with a higher homocystein level, the results showed that Iraqi males with this mutation are more likely to suffer from infertility.

Whole-genome analysis of human embryonic stem cells enables rational line selection based on genetic variation

Despite their widespread use in research, there has not yet been a systematic genomic analysis of human embryonic stem cell (hESC) lines at a single-nucleotide resolution. We therefore performed whole-genome sequencing (WGS) of 143 hESC lines and annotated their single-nucleotide and structural genetic variants. We found that while a substantial fraction of hESC lines contained large deleterious structural variants, finer-scale structural and single-nucleotide variants (SNVs) that are ascertainable only through WGS analyses were present in hESC genomes and human blood-derived genomes at similar frequencies. Moreover, WGS allowed us to identify SNVs associated with cancer and other diseases that could alter cellular phenotypes and compromise the safety of hESC-derived cellular products transplanted into humans. As a resource to enable reproducible hESC research and safer translation, we provide a user-friendly WGS data portal and a data-driven scheme for cell line maintenance and selection.

BAF-L Modulates Histone-to-Protamine Transition during Spermiogenesis

Maturing male germ cells undergo a unique developmental process in spermiogenesis that replaces nucleosomal histones with protamines, the process of which is critical for testicular development and male fertility. The progress of this exchange is regulated by complex mechanisms that are not well understood. Now, with mouse genetic models, we show that barrier-to-autointegration factor-like protein (BAF-L) plays an important role in spermiogenesis and spermatozoal function. BAF-L is a male germ cell marker, whose expression is highly associated with the maturation of male germ cells. The genetic deletion of BAF-L in mice impairs the progress of spermiogenesis and thus male fertility. This effect on male fertility is a consequence of the disturbed homeostasis of histones and protamines in maturing male germ cells, in which the interactions between BAF-L and histones/protamines are implicated. Finally, we show that reduced testicular expression of BAF-L represents a risk factor of human male infertility.

Association of Novel Single Nucleotide Polymorphisms of Genes Involved in Cell Functions with Male Infertility: A Study of Male Cases in Northwest Iran

Background

Infertility is a global health problem caused by various environmental and genetic factors. Male infertility accounts for 40-50% of all cases of infertility and approximately half of them are grouped as idiopathic with no definitive causes. Previous studies have suggested an association between some SNPs and infertility in men. In this study, an attempt was made to investigate the association of 7 different SNPs of 4 genes involved in common cell functions with male infertility.

Methods

MTHFR rs1801131 (T>G), MTHFR rs2274976 (G>A), FASLG rs80358238 (A>G), FASLG rs12079514 (A>C), GSTM1 rs1192077068 (G>A), BRCA2 rs4987117 (C>T), and BRCA2 rs11571833 (A>T) were genotyped in 120 infertile men with idiopathic azoospermia or severe oligospermia and 120 proven fertile controls using ARMS-PCR methods. Next, 30% of SNPs were regenotyped to confirm the results. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated using SPSS statistical software to evaluate the strength of association. The p<0.05 were considered statistically significant.

Results

Statistical analysis revealed significant association between MTHFR rs-2274976 AA variant (OR: 10.00, CI: 3.203-31.225), FASLG rs12079514 AC variant (OR: 0.412, CI: 0.212-0.800), and BRCA2 rs11571833 TT variant OR: 6.233, CI: 3.211-12.101) with male infertility, but there was no significant difference between case and control groups in MTHFR rs1801131 (p= 0.111), GSTM1 rs1192077068 (p=0.272), BRCA2 rs4987117 (p=0.221), and FASLG rs80358238 (p=0.161).

Conclusion

Our findings suggested that some novel polymorphisms including MTHFR rs2274976, FASLG rs12079514, and BRCA2 rs11571833 might be the possible predisposing risk factors for male infertility in cases with idiopathic azoospermia.

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

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

Strategies and Perspectives for UV Resonance Raman Applicability in Clinical Analyses of Human Sperm RNA

Developing a deeper knowledge about the impact of DNA and RNA epigenetic mutations on sperm production and fertilization performance is essential for selecting best quality samples in Assisted Reproductive Technologies (ART). Indeed, sperm RNAs adenine and guanine are likely to be methylated in low quality RNA sperm samples and their study requires the employment of techniques able to isolate high quality nucleic acids. UV resonance Raman spectroscopy represents a valuable tool that is able to monitor peculiar molecular modifications occurring predominantly in nucleic acids, being less sensitive to the presence of other biological compounds. In this work, we used an UV Resonance Raman (UVRR) setup coupled to a synchrotron radiation source tuned at 250 nm, in order to enhance sperm RNAs adenine and guanine vibrational signals, reducing also the impact of a fluorescence background typically occurring at lower energies. Despite that our protocol should be further optimized and further analyses are requested, our results support the concept that UVRR can be applied for setting inexpensive tools to be employed for semen quality assessment in ART.

Protective effect of saponin on sperm DNA fragmentation of mice treated with cyclophosphamide

Cyclophosphamide (CP) is a common chemotherapy drug with the testicular damage. The aim of this study was to investigate the effect of saponin (SP) on the toxicity of CP in the male reproductive system. Following an experimental pilot study for determining SP dose, 40 male mice (32 ± 3 g) were divided into five groups (n = 8): control, sham (normal saline 0.2 ml/day), CP (15 mg/kg/week, intraperitoneally), SP (2.5 mg/kg/day, intraperitoneally) and saponin group with cyclophosphamide (SP + CP). After treatment, the left testes were removed for the measurement of malonedialdehyde (MDA) and total antioxidant capacity (TAC) levels, and sperm DNA fragmentation was assessed by SDFA kit. In the CP group, a significant decrease in motility, viability, count, normal morphology and DNA fragmentation of spermatozoa and TAC was observed, while in MDA level, a significant increase was observed compared with the control group (p < 0.05). Attenuated sperm parameters in CP group improved significantly in SP + CP group (p < 0.05). According to the findings of this study, SP was able to alter the reproductive toxicity of CP in NMRI mice and increase the antioxidant capacity of the testis.

The I510V mutation in KLHL10 in a patient with oligoasthenoteratozoospermia

Oligoasthenoteratozoospermia is a human infertility syndrome caused by defects in spermatogenesis, spermiogenesis, and sperm maturation, and its etiology remains unclear. Kelch-like 10 (KLHL10) is a component of ubiquitin ligase E3 10 (KLHL10) and plays an important role in male fertility. Deletion or mutation of the Klhl10 gene in Drosophila or mice results in defects in spermatogenesis or sperm maturation. However, the molecular mechanisms by which KLHL10 functions remain elusive. In this study, we identified a missense mutation (c.1528A→G, p.I510V) in exon 5 of KLHL10, which is associated with oligoasthenoteratozoospermia in humans. To investigate the effects of this mutation on KLHL10 function and spermatogenesis and/or spermiogenesis, we generated mutant mice duplicating the amino acid conversion using the clustered regularly interspaced palindromic repeat/caspase 9 (CRISPR/Cas9) system and designated them Klhl10^I510V mice. However, the Klhl10^I510V mice did not exhibit any defects in testis development, spermatogenesis, or sperm motility at ten-weeks-of-age, suggesting that this mutation does not disrupt the KLHL10 function, and may not be the cause of male infertility in the affected individual with oligoasthenoteratozoospermia.

Reciprocal translocation and Robertsonian translocation in relation to semen parameters: A retrospective study and systematic review

Reciprocal translocation and Robertsonian translocation are known to be causative factors of male infertility. However, the association between autosomal reciprocal translocation, Robertsonian translocation and semen parameters remains controversial. We performed a retrospective study and systematic review to investigate semen parameters in patients with autosomal reciprocal translocation or Robertsonian translocation. We recruited a total of 1,033 controls, 723 reciprocal translocation carriers and 326 Robertsonian translocation carriers. Men in the control, reciprocal translocation and Robertsonian translocation groups had a median age of 32.0 (95% CI, 32.0-33.0), 32.0 (95% CI, 32.0-33.0) and 33.0 (95% CI, 32.0-33.0) years respectively. Results showed that sperm concentration, total number per ejaculate, total motility, progressive motility of autosomal reciprocal translocation and Robertsonian translocation carriers were statistically lower than controls (p < .001). Eleven studies featuring 794 patients were enrolled in this systematic review. Compared with controls, autosomal reciprocal translocation and Robertsonian translocation carriers showed lower sperm concentration, total motility, progressive motility and normal morphology. Our results support the conclusion that sperm concentration, total number per ejaculate, total motility and progressive motility are significantly lower in autosomal reciprocal translocation and Robertsonian translocation carriers than in controls.

Potential of testis-derived circular RNAs in seminal plasma to predict the outcome of microdissection testicular sperm extraction in patients with idiopathic non-obstructive azoospermia

STUDY QUESTION

Do testis-derived circular RNAs (circRNAs) in seminal plasma have potential as biomarkers to predict the outcome of microdissection testicular sperm extraction (micro-TESE) in patients with idiopathic non-obstructive azoospermia (NOA)?

SUMMARY ANSWER

Testis-derived circRNAs in the seminal plasma can indeed be used for predicting the outcome of micro-TESE in patients with idiopathic NOA.

WHAT IS KNOWN ALREADY

Micro-TESE is an effective method to obtain sperm samples from patients with idiopathic NOA. However, its success rate is only 40-50% in such patients.

STUDY DESIGN, SIZE, DURATION

Six idiopathic NOA patients with different micro-TESE results were included as the discovery cohort. Their testicular tissues were used for extracting and sequencing circRNAs. Five circRNAs with the most significantly different expression levels were selected for further verification.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Fifty-two patients with idiopathic NOA were included as the validation cohort. Preoperative seminal plasma samples of 52 patients with idiopathic NOA and 25 intraoperative testicular tissues were collected and divided into 'success' and 'failure' groups according to the results of micro-TESE. Quantitative real-time polymerase chain reaction was performed to verify differences in the expression levels of the selected circRNAs between the two groups in the testicular tissues and seminal plasma.

MAIN RESULTS AND THE ROLE OF CHANCE

Whether at the seminal plasma or testicular tissue level, the differences in the expression levels of the three circRNAs (hsa_circ_0000277, hsa_circ_0060394 and hsa_circ_0007773) between the success and failure groups were consistent with the sequencing results. A diagnostic receiver operating curve (ROC) analysis of the AUC indicated excellent diagnostic performance of these circRNAs in seminal plasma in predicting the outcome of micro-TESE (AUC values: 0.920, 0.928 and 0.891, respectively). On the basis of least absolute shrinkage and selection operator (LASSO) logistic regression, the three circRNAs were combined to construct a new prediction model. The diagnostic ROC curve analysis of the model showed an AUC value of 0.958. The expression levels of these circRNAs in seminal plasma using three normospermic volunteer samples remained stable after 48 h at room temperature.

LARGE SCALE DATA

NA.

LIMITATIONS, REASONS FOR CAUTION

This was a single-center retrospective study with relatively few cases. The functions of these circRNAs, as well as their relationship with spermatogenesis, have not yet been established.

WIDER IMPLICATIONS OF THE FINDINGS

Testis-derived circRNAs in seminal plasma can reflect the microenvironment of the testis and can be used as reliable biomarkers to screen patients with idiopathic NOA who might be suitable for micro-TESE.

STUDY FUNDING/COMPETING INTEREST(S)

This article was funded by the National Natural Science Foundation of China (Grant no. 81871151). There were no competing interests.

Prevalence of Y chromosome microdeletion in azoospermia factor subregions among infertile men from West Bengal, India

Background

Etiology of male infertility is intriguing and Y chromosome microdeletion within azoospermia factor (AZF) sub‐regions is considered major cause. We conducted a screening for Y chromosome microdeletion in an infertile male cohort from West Bengal, India to characterize Y chromosome microdeletion among infertile men.

Methods

We recruited case subjects that were categorized on the basis of sperm count as azoospermia (N = 63), severe oligozoospermia (N = 38), and oligozoospermia (N = 17) and compared them with age, demography, and ethnicity matched healthy proven fertile control males (N = 84). Sequence Tagged Site makers and polymerase chain reaction based profiling of Y chromosome was done for AZF region and SRY for cases and controls.

Results

We scored 16.1% of cases (19 out of 118) that bear one or more microdeletions in the studied loci and none among the controls. The aberrations were more frequent among azoospermic males (17 of 19) than in severe oligozoospermic subjects (2 of 19).

Conclusion

Our study provides the results of screening of the largest Bengali infertile men sample genotyped with the maximum number of STS markers spanning the entire length of Y chromosome long arm. Y chromosome microdeletion is a significant genetic etiology of infertility among Bengali men.

Anti-Müllerian hormone concentration as an indicator of female general health status: a cross-sectional study

RESEARCH QUESTION

To evaluate the correlation between clinical and hormonal parameters and comorbidity burden in Caucasian women presenting for fertility treatment.

DESIGN

Monocentric cross-sectional study including a cohort of 3163 Caucasian women seeking medical care for fertility treatment. All patients underwent centralized laboratory testing for hormonal assessment. Complete clinical and laboratory data from the entire cohort were retrospectively analysed. Comorbidity burden score was assessed by the Charlson Comorbidity Index (CCI; categorized as 0 versus 1 versus ≥2).

RESULTS

Descriptive statistics and regression models tested the associations between clinical and laboratory parameters and CCI. Among the entire cohort of patients, a CCI = 0 was found in 2977 women (94.1%), and CCI = 1 and CCI ≥2 were found in 113 (3.6%) and 73 (2.3%) patients, respectively. Age (P = 0.009), gravidity (P = 0.001), anti-Müllerian hormone (AMH, P < 0.001) and TSH (P = 0.003) values were significantly different among CCI groups. In regression models, age at presentation and AMH emerged as independent indicators of CCI ≥ 1. Age at presentation <36 years (odds ratio [OR] 1.742, 95% confidence interval [CI] 1.284-2.364) and an AMH concentration ≤2.3 ng/ml (OR 1.864, 95% CI 1.29-2.69) were the most informative cut-off values for CCI ≥ 1 in the study population.

CONCLUSIONS

A younger age at presentation and lower AMH concentrations are significant independent indicators of decreased general health in women requiring clinical evaluation for fertility treatment. As observed for sperm parameters in men, AMH might serve as a proxy of women's general health status.

Gene Alterations and Expression Spectrum of NANOS3 in Nonobstructive Azoospermia

Nanos3, a zinc finger RNA-binding protein, suppresses the apoptosis in primordial germ cells (PGCs) during migration to gonads and maintains the PGC population. The genetic variations and expression of NANOS3 in patients with non-obstructive azoospermia (NOA) were evaluated in this study. The study included 100 idiopathic infertile men with NOA and 100 fertile men as the as the case and control groups, respectively. NANOS3 gene variations were analyzed using the standard polymerase chain reaction (PCR) and sequencing. For mRNA and protein expression analysis, testicular biopsy specimens from 27 patients including 9 obstructive azoospermia (OA), 9 maturation arrest (MA), and 9 Sertoli cell-only syndromes (SCOS) were collected and evaluated using the real-time PCR technique and immunohistochemistry. Although the evaluation of the 5`UTR regulatory region has shown the significant difference in the numbers of TG repeats in rs11182456 between groups, the odd ratio was not strong enough to consider that as a certain risk factor lead to azoospermia and infertility. Meanwhile, NANOS3 expression at mRNA level had a significant difference among OA, SCOS, and MA groups.

Nuclear translocation of MTL5 from cytoplasm requires its direct interaction with LIN9 and is essential for male meiosis and fertility

Meiosis is essential for the generation of gametes and sexual reproduction, yet the factors and underlying mechanisms regulating meiotic progression remain largely unknown. Here, we showed that MTL5 translocates into nuclei of spermatocytes during zygotene-pachytene transition and ensures meiosis advances beyond pachytene stage. MTL5 shows strong interactions with MuvB core complex components, a well-known transcriptional complex regulating mitotic progression, and the zygotene-pachytene transition of MTL5 is mediated by its direct interaction with the component LIN9, through MTL5 C-terminal 443–475 residues. Male Mtl5^c-mu/c-mu mice expressing the truncated MTL5 (p.Ser445Arg fs*3) that lacks the interaction with LIN9 and is detained in cytoplasm showed male infertility and spermatogenic arrest at pachytene stage, same as that of Mtl5 knockout mice, indicating that the interaction with LIN9 is essential for the nuclear translocation and function of MTL5 during meiosis. Our data demonstrated MTL5 translocates into nuclei during the zygotene-pachytene transition to initiate its function along with the MuvB core complex in pachytene spermatocytes, highlighting a new mechanism regulating the progression of male meiosis.

Meiosis is essential for spermatogenesis and male fertility. However, the factors regulating the progression of meiosis remain largely unknown. We reported the testis specific protein MTL5 translocated into the nuclei of spermatocytes at the zygotene-pachytene transition by direct interaction with LIN9, which is an essential component of MuvB core complex, to promote meiotic progression beyond the pachytene stage. We also showed that MTL5 pulls down MYBL1 and all of the MuvB core complex (except LIN54) in spermatocytes. Given the known role of the MuvB core complex as a cell cycle regulator in mitotic cells, we suggested that MTL5 promotes meiotic progression along with the MuvB core complex to ensure male fertility. Our results indicated a novel function of the MuvB complex in male meiosis and also shed light on the master regulator proteins that control meiotic progression at the pachytene stage. MTL5 is a novel and germ-cell specific regulator of cell cycle progression to function at a specific stage by nuclear translocation in meiosis.

Stereological properties of seminiferous tubules in infertile men with chromosomal and genetic abnormalities

BACKGROUND

Male infertility is caused by genetic anomalies in 15%-30% of cases. This study aimed to determine stereological properties of seminiferous tubules in infertile men with genetic anomalies, including Klinefelter syndrome (KS), Y chromosome microdeletions (MYC) and CFTR gene mutations (CFTR), and to compare them to seminiferous tubules of men with obstructive azoospermia of non-genetic origin (control group).

METHODS

The study was conducted on 28 human testis biopsy specimens obtained from 14 patients with MYC, 18 samples from 9 patients with KS, and 6 samples from 3 patients with CFTR. Whenever possible, a bilateral biopsy was included in the study. The control group had 33 samples from 18 patients (3 of them with a solitary testis). Qualitative and quantitative (stereological) analysis of seminiferous tubules (including the status of spermatogenesis, volume, surface area, length and number of tubules) were performed in all groups.

RESULTS

Qualitative histological analysis revealed significant impairment of spermatogenesis in KS and MYC, whereas testicular parenchyma was fully maintained in CFTR and control groups. Spermatogenesis was most seriously impaired in KS. All stereological parameters were significantly lower in KS and MYC, compared to the CFTR and control groups. The total volume, surface and length of seminiferous tubules were significantly lower in KS compared with MYC.

CONCLUSIONS

Stereological analysis is valuable in evaluating male infertility, whereas qualitative histological analysis can be helpful in assessing sperm presence in testicular tissue of patients with KS or MYK undergoing TESE.

Evaluation of immune status in testis and macrophage polarization associated with testicular damage in patients with nonobstructive azoospermia

OBJECTIVE

Immune cells residing in the testicular interstitial space form the immunological microenvironment of the testis. They are assumed to play a role in maintaining testicular homeostasis and immune privilege. However, the immune status and related cell polarization in patients with nonobstructive azoospermia (NOA) remains poorly characterized. System evaluation of the testis immunological microenvironment in NOA patients may help to reveal the mechanisms of idiopathic azoospermia.

STUDY DESIGN

The gene expression patterns of immune cells in normal human testes were systematically analyzed by single-cell RNA sequencing (scRNA-seq) and preliminarily verification by the human protein atlas (HPA) online database. The immune cell infiltration profiles and immune status of patients with NOA was analyzed by single-sample gene set enrichment analysis (ssGSEA) and gene set variation analysis (GSVA) based on four independent public microarray datasets (GSE45885, GSE45887, GSE9210, and GSE145467), obtained from Gene Expression Omnibus (GEO) online database. The relationship between immune cells and spermatogenesis score was further analyzed by Spearman correlation analysis. Finally, immunohistochemistry (IHC) staining was performed to identify the main immune cell types and their polarization status in patients with NOA.

RESULTS

Both scRNA-seq and HPA analysis showed that testicular macrophages represent the largest pool of immune cells in the normal testis, and also exhibit an attenuated inflammatory response by expressing high levels of tolerance proteins (CD163, IL-10, TGF-β, and VEGF) and reduced expression of TLR signaling pathway-related genes. Correlation analysis revealed that the testicular immune score and macrophages including M1 and M2 macrophages were significantly negatively correlated with spermatogenesis score in patients with NOA (GSE45885 and GSE45887). In addition, the number of M1 and M2 macrophages was significantly higher in patients with NOA (GSE9210 and GSE145467) than in normal testis. GSVA analysis indicated that the immunological microenvironment in NOA tissues was manifested by activated immune system and pro-inflammatory status. IHC staining results showed that the number of M1 and M2 macrophages was significantly higher in NOA tissues than in normal testis and negatively correlated with the Johnson score.

CONCLUSION

Testicular macrophage polarization may play a vital role in NOA development and is a promising potential therapeutic target.

Application of Stem Cell Therapy for Infertility

Infertility creates an immense impact on the psychosocial wellbeing of affected couples, leading to poor quality of life. Infertility is now considered to be a global health issue affecting approximately 15% of couples worldwide. It may arise from factors related to the male (30%), including varicocele, undescended testes, testicular cancer, and azoospermia; the female (30%), including premature ovarian failure and uterine disorders; or both partners (30%). With the recent advancement in assisted reproduction technology (ART), many affected couples (80%) could find a solution. However, a substantial number of couples cannot conceive even after ART. Stem cells are now increasingly being investigated as promising alternative therapeutics in translational research of regenerative medicine. Tremendous headway has been made to understand the biology and function of stem cells. Considering the minimum ethical concern and easily available abundant resources, extensive research is being conducted on induced pluripotent stem cells (iPSCs) and mesenchymal stem cells (MSC) for their potential application in reproductive medicine, especially in cases of infertility resulting from azoospermia and premature ovarian insufficiency. However, most of these investigations have been carried out in animal models. Evolutionary divergence observed in pluripotency among animals and humans requires caution when extrapolating the data obtained from murine models to safely apply them to clinical applications in humans. Hence, more clinical trials based on larger populations need to be carried out to investigate the relevance of stem cell therapy, including its safety and efficacy, in translational infertility medicine.

Analysis of STAG3 variants in Chinese non-obstructive azoospermia patients with germ cell maturation arrest

STAG3 is essential for male meiosis and testis of male Stag3^-/- mice shows the histopathological type of germ cell maturation arrest (MA). Whether variants of the STAG3 gene exist in Chinese idiopathic non-obstructive azoospermia (NOA) patients needs to be determined. We recruited 58 Chinese NOA men with MA who underwent testis biopsy and 192 fertile men as the control group. The 34 exons of the STAG3 gene were amplified using polymerase chain reaction (PCR) and sequenced. We identified eight novel single nucleotide polymorphisms (SNPs), including two missense SNPs (c.433T > C in exon2 and c.553A > G in exon3), three synonymous SNPs (c.539G > A, c.569C > T in exon3, and c.1176C > G in exon8), and three SNPs in introns. The allele and genotype frequencies of the novel and other SNPs have no significant differences between two groups. Our results indicated that variants in the coding sequence of the STAG3 gene were uncommon in NOA patients with MA in Chinese population. Future studies in large cohorts of different ethnic populations will be needed to determine the association between the STAG3 gene and NOA.

Tsga8 is required for spermatid morphogenesis and male fertility in mice

During spermatogenesis, intricate gene expression is coordinately regulated by epigenetic modifiers, which are required for differentiation of spermatogonial stem cells (SSCs) contained among undifferentiated spermatogonia. We have previously found that KMT2B conveys H3K4me3 at bivalent and monovalent promoters in undifferentiated spermatogonia. Because these genes are expressed late in spermatogenesis or during embryogenesis, we expect that many of them are potentially programmed by KMT2B for future expression. Here, we show that one of the genes targeted by KMT2B, Tsga8, plays an essential role in spermatid morphogenesis. Loss of Tsga8 in mice leads to male infertility associated with abnormal chromosomal distribution in round spermatids, malformation of elongating spermatid heads and spermiation failure. Tsga8 depletion leads to dysregulation of thousands of genes, including the X-chromosome genes that are reactivated in spermatids, and insufficient nuclear condensation accompanied by reductions of TNP1 and PRM1, key factors for histone-to-protamine transition. Intracytoplasmic sperm injection (ICSI) of spermatids rescued the infertility phenotype, suggesting competency of the spermatid genome for fertilization. Thus, Tsga8 is a KMT2B target that is vitally necessary for spermiogenesis and fertility.

DDB1- and CUL4-associated factor 8 plays a critical role in spermatogenesis

Cullin-RING E3 ubiquitin ligase (CRL)-4 is a member of the large CRL family in eukaryotes. It plays important roles in a wide range of cellular processes, organismal development, and physiological and pathological conditions. DDB1- and CUL4-associated factor 8 (DCAF8) is a WD40 repeat-containing protein, which serves as a substrate receptor for CRL4. The physiological role of DCAF8 is unknown. In this study, we constructed Dcaf8 knockout mice. Homozygous mice were viable with no noticeable abnormalities. However, the fertility of Dcaf8-deficient male mice was markedly impaired, consistent with the high expression of DCAF8 in adult mouse testis. Sperm movement characteristics, including progressive motility, path velocity, progressive velocity, and track speed, were significantly lower in Dcaf8 knockout mice than in wild-type (WT) mice. However, the total motility was similar between WT and Dcaf8 knockout sperm. More than 40% of spermatids in Dcaf8 knockout mice showed pronounced morphological abnormalities with typical bent head malformation. The acrosome and nucleus of Dcaf8 knockout sperm looked similar to those of WT sperm. In vitro tests showed that the fertilization rate of Dcaf8 knockout mice was significantly reduced. The results demonstrated that DCAF8 plays a critical role in spermatogenesis, and DCAF8 is a key component of CRL4 function in the reproductive system.

Telomere Length and Male Fertility

Over the past decade, telomeres have attracted increasing attention due to the role they play in human fertility. However, conflicting results have been reported on the possible association between sperm telomere length (STL) and leukocyte telomere length (LTL) and the quality of the sperm parameters. The aim of this study was to run a comprehensive study to investigate the role of STL and LTL in male spermatogenesis and infertility. Moreover, the association between the sperm parameters and 11 candidate single nucleotide polymorphisms (SNPs), identified in the literature for their association with telomere length (TL), was investigated. We observed no associations between sperm parameters and STL nor LTL. For the individual SNPs, we observed five statistically significant associations with sperm parameters: considering a p < 0.05. Namely, ACYP2˗rs11125529 and decreased sperm motility (p = 0.03); PXK˗rs6772228 with a lower sperm count (p = 0.02); NAF1˗rs7675998 with increased probability of having abnormal acrosomes (p = 0.03) and abnormal flagellum (p = 0.04); ZNF208˗rs8105767 and reduction of sperms with normal heads (p = 0.009). This study suggests a moderate involvement of telomere length in male fertility; however, in our analyses four SNPs were weakly associated with sperm variables, suggesting the SNPs to be pleiotropic and involved in other regulatory mechanisms independent of telomere homeostasis, but involved in the spermatogenic process.

A novel frameshift mutation in ubiquitin-specific protease 26 gene in a patient with severe oligozoospermia

Ubiquitin-specific protease 26 (USP26) encodes a predicted protein containing his- and cys- domains that are conserved among deubiquitinating enzymes. USP26 is specifically expressed in testis tissue and is a potential infertility gene. In the present study, we performed genetic testing related to spermatogenesis impairment in a patient with idiopathic severe oligozoospermia to identify the cause. The patient underwent clinical examination and reproductive hormone testing. Genes associated with male infertility, including USP26, were assessed by targeted exome sequencing. A novel frameshift mutation, c.2195delT (p.Phe732Serfs*14), was identified in USP26. This frameshift mutation was located in residue 732 of USP26 gene, leading to loss of the conserved deubiquitinating enzyme His-domain and producing a truncated protein of 744 amino acids. Bioinformatics analysis revealed this mutation to be pathogenic. A novel framshift mutation c.2195delT (p.Phe732Serfs*14) in USP26 gene was reported to be associated with male infertility in a Chinese patient with severe oligozoospermia.

Genetic testing for men with infertility: techniques and indications

Genetic testing is an integral component in the workup of male infertility as genetic conditions may be responsible for up to 15% of all cases. Currently, three genetic tests are commonly performed and recommended by major urologic associations: karyotype analysis (KA), Y-chromosome microdeletion testing, and CFTR mutation testing. Despite widespread adoption of these tests, an etiology for infertility remains elusive in up to 80% of cases. Recent work has identified intriguing new targets for genetic testing which may soon see clinical relevance. This review will discuss the indications and techniques for currently offered genetic tests and briefly explore ongoing research directions within this field.

Complementary and Alternative Medicine Usage and Its Determinant Factors Among Infertile Men in Iran

Objective: This study aimed to assess the use of some Complementary and Alternative Medicine (CAM) techniques in infertile men. Materials and methods: This cross-sectional study was conducted on 102 infertile men referred to the only center of infertility in Kerman, Iran using convenience sampling. Data were collected using a two-part researcher-made questionnaire and analyzed using descriptive and analytical statistics (chi-square test and logistic regression) with SPSS 16. Results: According to the present study, 72.5% of subjects used at least one of the CAM methods in the past year. Among them 28.4% of the subjects have used one CAM technique, 13.7% have used two techniques, 8.8% have used three techniques, 9.8% have used four techniques, and 11.8% have used more than four techniques since the last year. None of the socio-demographic characteristics had significant association with being the user of complementary and alternative medicines. Conclusion: The results showed that almost three quarters of the infertile men used CAM indicating a high prevalence of CAM usage among them.

Infertility network and hub genes for nonobstructive azoospermia utilizing integrative analysis

Non-obstructive azoospermia (NOA) is the most severe form of male infertility owing to the absence of sperm during ejaculation as a result of failed spermatogenesis. The molecular mechanisms of NOA have not been well studied. Here, we revealed the dysregulated differentially expressed genes in NOA and related signaling pathways or biological processes. Cluster features of biological processes include spermatogenesis, fertilization, cilium movement, penetration of zona pellucida, sperm chromatin condensation, and being significantly enriched metabolic pathways in proximal tubule bicarbonate reclamation, aldosterone synthesis and secretion, glycolysis and glycogenesis pathways in NOA using Gene Ontology analysis and pathway enrichment analysis. The NOA gene co-expression network was constructed by weighted gene co-expression network analysis to identify the hub genes (CHD5 and SPTBN2). In addition, we used another Gene Expression Omnibus dataset (GSE45887) to validate these hub genes. Furthermore, we used the Seurat package to classify testicular tissue cells from NOA patients and to characterize the differential expression of hub genes in different cell types from different adult males based on the scRNA-seq dataset (GSE106487). These results provide new insights into the pathogenesis of NOA. Of particular note, CHD5 and SPTBN2 may be potential biomarkers for the diagnosis and treatment of NOA.

Y chromosome structural variation in infertile men detected by targeted next-generation sequencing

PURPOSE

To provide a validated method to identify copy number variation (CNV) in regions of the Y chromosome of infertile men by next-generation sequencing (NGS).

METHODS

Semen analysis was used to determine the quality of semen and diagnose infertility. Deletion of the azoospermia factor (AZF) region in the Y chromosome was detected by a routine sequence-tagged-site PCR (STS-PCR) method. We then used the NGS method to detect CNV in the AZF region, including deletions and duplications.

RESULTS

A total of 326 samples from male infertility patients, family members, and sperm donors were studied between January 2011 and May 2017. AZF microdeletions were detected in 120 patients by STS-PCR, and these results were consistent with the results from NGS. In addition, of the 160 patients and male family members who had no microdeletions detected by STS-PCR, 51 cases were found to exhibit Y chromosome structural variations by the NGS method (31.88%, 51/160). No microdeletions were found in 46 donors by STS-PCR, but the NGS method revealed 11 of these donors (23.91%, 11/46) carried structural variations, which were mainly in the AZFc region, including partial deletions and duplications.

CONCLUSION

The established NGS method can replace the conventional STS-PCR method to detect Y chromosome microdeletions. The NGS method can detect CNV, such as partial deletion or duplication, and provide details of the abnormal range and size of variations.