Meiosis is a specialized cell division process that generates gametes for sexual reproduction. However, the factors and underlying mechanisms involving meiotic progression remain largely unknown, especially in humans. Here, it is first showed that HSF5 is associated with human spermatogenesis. Patients with a pathogenic variant of HSF5 are completely infertile. Testicular histologic findings in the patients reveal rare postmeiotic germ cells resulting from meiotic prophase I arrest. Hsf5 knockout (KO) mice confirms that the loss of HSF5 causes defects in meiotic recombination, crossover formation, sex chromosome synapsis, and sex chromosome inactivation (MSCI), which may contribute to spermatocyte arrest at the late pachytene stage. Importantly, spermatogenic arrest can be rescued by compensatory HSF5 adeno-associated virus injection into KO mouse testes. Mechanistically, integrated analysis of RNA sequencing and chromatin immunoprecipitation sequencing data revealed that HSF5 predominantly binds to promoters of key genes involved in crossover formation (e.g., HFM1, MSH5 and MLH3), synapsis (e.g., SYCP1, SYCP2 and SYCE3), recombination (TEX15), and MSCI (MDC1) and further regulates their transcription during meiotic progression. Taken together, the study demonstrates that HSF5 modulates the transcriptome to ensure meiotic progression in humans and mice. These findings will aid in genetic diagnosis of and potential treatments for male infertility.

Non-obstructive azoospermia (NOA) resulting from primary spermatogenic failure represents one of the most severe forms of male infertility, largely because therapeutic options are very limited. Beyond their diagnostic value, genetic tests for NOA also hold prognostic potential. Specifically, genetic diagnosis enables the establishment of genotype-testicular phenotype correlations, which, in some cases, provide a negative predictive value for testicular sperm extraction (TESE), thereby preventing unnecessary surgical procedures. In this study, we employed whole-genome sequencing (WGS) to investigate two generations of an Iranian family with NOA and identified a homozygous splicing variant in TDRKH (NM_001083965.2: c.562-2A>T). TDRKH encodes a conserved mitochondrial membrane-anchored factor essential for piRNA biogenesis in germ cells. In Tdrkh knockout mice, de-repression of retrotransposons in germ cells leads to spermatogenic arrest and male infertility. Previously, our team reported TDRKH involvement in human NOA cases through the investigation of a North African cohort. This current study marks the second report of TDRKH\'s role in NOA and human male infertility, underscoring the significance of the piRNA pathway in spermatogenesis. Furthermore, across both studies, we demonstrated that men carrying TDRKH variants, similar to knockout mice, exhibit complete spermatogenic arrest, correlating with failed testicular sperm retrieval.

UNASSIGNED: In an era of advanced maternal age, there is less conclusive evidence regarding the treatment outcomes of varicocele repair for assisted reproductive technology (ART). Progress in basic research on varicocele is notable whereas there are many clinically relevant points to discuss.
UNASSIGNED: Based on our experience with more than 2000 cases of microsurgical varicocele repair, we focused on the effectiveness of varicocele repair, pathophysiology, surgical approaches, contributions to ART, sperm DNA fragmentation, and varicocele-associated azoospermia in this review with the aim of identifying clearer directions for basic and clinical research on varicocele.
UNASSIGNED: Microsurgical low ligation for varicocele repair is expected to remain the gold standard for surgical therapy. Based on the findings from a number of systematic reviews and meta-analyses, negative opinions regarding the efficacy of microsurgical varicocele repair in male infertility treatment have become virtually nonexistent. However, the majority of evidence regarding surgical indications and effectiveness pertains to improvements in semen parameters or non-ART pregnancy rates.
UNASSIGNED: Further understandings regarding to pathophysiology of varicocele will likely be gained through comprehensive genetic, transcriptomic, and epigenetic analyses using blood and testicular samples from humans and we hope to develop new diagnostic methods and pharmacotherapy.

Infertility affects an estimated 10 to 15 percent of couples worldwide, with approximately half of the cases attributed to male-related issues. Most men diagnosed with infertility exhibit symptoms such as oligospermia, asthenospermia, azoospermia, and compromised sperm quality. Spermatogenesis is a complex and tightly coordinated process of germ cell differentiation, precisely regulated at transcriptional, posttranscriptional, and translational levels to ensure stage-specific gene expression during the development of spermatogenic cells and normal spermiogenesis. N6-methyladenosine (m6A) stands out as the most prevalent modification on eukaryotic mRNA, playing pivotal roles in various biological processes, including mRNA splicing, transportation, and translation. RNA methylation modification is a dynamic and reversible process primarily mediated by \"writers\", removed by \"erasers\", and recognized by \"readers\". In mammals, the aberrant methylation modification of m6A on mRNA is associated with a variety of diseases, including male infertility. However, the precise involvement of disrupted m6A modification in the pathogenesis of human male infertility remains unresolved. Intriguingly, a significant correlation has been found between the expression levels of m6A regulators in the testis and the severity of sperm concentration, motility, and morphology. Aberrant expression patterns of m6A regulatory proteins have been detected in anomalous human semen samples, including those of oligospermia, asthenozoospermia, and azoospermia. Furthermore, the examination of both sperm samples and testicular tissues revealed abnormal mRNA m6A modification, leading to reduced sperm motility and concentration in infertile men. Consequently, it is hypothesized that dysregulation of m6A modification might serve as an integral link in the mechanism of male infertility. This paper presents a comprehensive review of the recent discoveries regarding the spatial and temporal expression dynamics of m6A regulators in testicular tissues and the correlation between deregulated m6A regulators and human male infertility. Previous studies predominantly utilized constitutive or conditional knockout animal models for testicular phenotypic investigations. However, gene suppression in additional tissues could potentially influence the testis in constitutive knockout models. Furthermore, considering the compromised spermatogenesis observed in constitutive animals, distinguishing between the indirect effects of gene depletion on testicular development and its direct impact on the spermatogenic process is challenging, due to their intricate relationship. Such confounding factors might compromise the validity of the findings. To address this challenge, an inducible and conditional gene knockout model may serve as a superior approach. To date, nearly all reported studies have concentrated solely on the level changes of m6A and its regulators in germs cells, while the understanding of the function of m6A modification in testicular somatic cells remains limited. Testicular somatic cells, including peritubular myoid cells, Sertoli cells, and Leydig cells, play indispensable roles during spermatogenesis. Hence, comprehensive exploration of m6A modification within these cells as an additional crucial regulatory mechanism is warranted. In addition, exploration into the presence of unique methylation mechanisms or m6A regulatory factors within the testes is warranted. To elucidate the role of m6A modification in germ cells and testicular somatic cells, detailed experimental strategies need to be implemented. Among them, manipulation of the levels of key enzymes involved in m6A methylation and demethylation might be the most effective approach. Moreover, comprehensive analysis of the gene expression profiles involved in various signaling pathways, such as Wnt/β-catenin, Ras/MAPK, and Hippo, in m6A-modified germ cells and testicular somatic cells can provide more insight into its regulatory role in the spermatogenesis process. Further research in this area could provide valuable insights for developing innovative strategies to treat male infertility. Finally, considering the mitigation impact of m6A imbalance regulation on disease, investigation concerning whether restoring the equilibrium of m6A modification regulation can restore normal spermatogenesis function is essential, potentially elucidating the pivotal clinical significance of m6A modulation in male infertility.

This study aims to investigate the effect of arsenic exposure on urinary levels of arsenic metabolites, semen parameters, and testosterone concentrations. A systematic comprehensive literature search was conducted up till 31st January 2024 using Embase, MEDLINE/Pubmed, and Scopus. This study adopted the Population Exposure Comparator Outcome and Study Design (PECOS) framework. Four studies with a total of 380 control subjects and 347 exposed men were included. Arsenic exposure significantly increased urinary levels of total arsenic (Mean Difference (MD) - 53.35 [95 % Confidence Interval (CI): - 100.14, - 6.55] P= 0.03), and reduced primary arsenic methylation index (PMI) (MD 0.22 [95 % CI: 0.14, 0.31] P< 0.00001), semen volume (MD 0.30 [95 % CI: 0.05, 0.54] P= 0.02) and total testosterone (MD 0.48 [95 % CI: 0.23, 0.73] P= 0.0002). In addition, arsenic exposure marginally reduced sperm concentration (MD 25.04 [95 % CI: - 45.42, 95.50] P= 0.49) and total sperm motility (MD 22.89 [95 % CI: - 14.15, 59.94] P= 0.23). The present meta-analysis demonstrates that arsenic exposure lowers semen quality and testosterone levels. Since the general human population is exposed to arsenic occupationally or domestically, adequate strategic measures should be put in place to limit arsenic exposure in an attempt to preserve semen quality. In addition, studies investigating interventions that may inhibit the bioaccumulation of arsenic in men who are exposed are recommended.

BACKGROUND: Obesity-associated male infertility is a common complication of obesity and has been increasing in prevalence. Blautia wexlerae has modulation effects on obesity. However, the action of B. wexlerae on obesity-associated male infertility is unclear. The nod-like receptor protein 3 (NLRP3) inflammasome has become a major target for addressing many diseases, including obesity-associated male infertility. This study aims to investigate the action of B. wexlerae on obesity-associated male infertility and the influence of B. wexlerae on NLRP3 inflammasome.
METHODS: The fecal samples were collected from 60 infertile men with or without obesity and 30 healthy men. The obesity mice model was established through high-fat diet (HFD) induction. The mating assays evaluated the male infertility of obese mice. A mouse-derived spermatogonia (GC-1 spg) cell viability was detected using the Cell Counting Kit-8 assay. The reactive oxygen species (ROS) were assessed using flow cytometry. Furthermore, immunofluorescence, enzyme-linked immunosorbent assay, and western blotting were applied to measure the gene expressions.
RESULTS: Blautia wexlerae was decreased and negatively correlated with interleukin-1 beta (IL-1β) or IL-18 levels in infertile men with obesity. On the other hand, B. wexlerae improved the mating capability of obese male mice and suppressed oxidative stress and NLRP3 inflammasome via the activation of the acetate receptor. Furthermore, sodium acetate regulated oxidative stress and NLRP3 inflammasome via the activation of the acetate receptor in GC-1 spg cells in vitro.
CONCLUSIONS: The administration of Blautia wexlerae improved obesity-associated male infertility and regulated oxidative stress and NLRP3 inflammasome activities. In general, its administration may be an effective strategy for the treatment of obesity-associated male infertility.

BACKGROUND: Infertility impacts 16% of North American couples, with male factor infertility contributing to ∼30% of cases. Reproductive hormones, especially testosterone, are essential for spermatogenesis. Age-independent population-level decline in testosterone concentrations over the past few decades has been proposed to be a result of diet and lifestyle changes. Vitamin B12 is present in the testes and has been suggested as an adjuvant nutritional therapy for male infertility due to its potential to improve sperm parameters. However, evidence examining the relationship between vitamin B12 and reproductive hormones is limited.
OBJECTIVE: The objective was to cross-sectionally examine the relationship between serum vitamin B12 and male reproductive hormones (luteinizing hormone, follicular stimulating hormone, total testosterone, estradiol and prolactin).
METHODS: Men with infertility (n = 303) were recruited from Mount Sinai Hospital in Toronto, Canada. Serum was analyzed for vitamin B12 and reproductive hormones. Statistical analyses included non-parametric Spearman\'s rank correlation coefficient, linear regression, logistic regression and effect modification by age and BMI linear regressions.
RESULTS: An independent monotonic relationship between serum vitamin B12 and total testosterone (rho = 0.19, P = 0.001) was observed. Serum vitamin B12 was linearly associated with total testosterone (unadjusted ß = 0.0007, P = 0.008 and adjusted ß = 0.0005, P = 0.03). Compared to individuals in the lowest tertile of serum vitamin B12, those in the middle tertile (adjusted OR = 0.48, 95% CI [0.25, 0.93], P = 0.03) and the highest tertile (unadjusted OR = 0.41, 95% CI [0.22, 0.77], P = 0.005 and adjusted OR = 0.44, 95% CI [0.22, 0.87], P = 0.02) had reduced odds of testosterone deficiency.
CONCLUSIONS: These findings suggest that among men with infertility, low serum vitamin B12 is associated with higher risk of testosterone deficiency and impaired androgenic hormonal profiles that impact spermatogenesis and consequently, fertility.

BACKGROUND: Dysfunction of motile cilia, including respiratory cilia and sperm flagella, typically leads to primary ciliary dyskinesia and male infertility or low fertility in humans. Genetic defects of LRRC6 have been associated with primary ciliary dyskinesia and asthenozoospermia due to abnormal ultrastructure of ciliated axonemes.
OBJECTIVE: To identify novel mutations of the LRRC6 gene related to multiple morphological abnormalities of the sperm flagella and male infertility and investigate the underlying molecular mechanisms involved.
METHODS: The LRRC6 mutations were identified by whole exome sequencing and confirmed with Sanger sequencing. Papanicolaou staining, scanning, and transmission electron microscopy were performed to investigate the morphological and ultrastructural characteristics of spermatozoa. Further tandem mass tagging proteomics analyses were performed to explore the effect of mutations and confirmed by immunostaining and western blotting. Intracytoplasmic sperm injection was applied for the assisted reproductive therapy of males harboring biallelic LRRC6 mutations.
RESULTS: In this study, we identified a novel homozygous LRRC6 mutation in a consanguineous family, characterized by asthenozoospermia and primary ciliary dyskinesia. Further Semen parameter and morphology analysis demonstrate that the novel LRRC6 mutation leads to a significant reduction in sperm flagella length, a decrease in sperm progressive motility parameters, and abnormalities of sperm ultrastructure. Specifically, the absence of outer dynein arms and inner dynein arms, and incomplete mitochondrial sheath in the flagellar mid-piece were observed by transmission electron microscopy. In addition, tandem mass tagging proteomics analysis revealed that spermatozoa obtained from patients harboring the LRRC6 mutation exhibited a significant decrease in the expression levels of proteins related to the assembly and function of dynein axonemal arms. Functional analysis revealed that this novel LRRC6 mutation disrupted the function of the leucine-rich repeat containing 6 protein, which in turn affects the expression of the dynein arm proteins and leucine-rich repeat containing 6-interacting proteins CCDC40, SPAG1, and ZMYND10. Finally, we reported a successful pregnancy through assisted reproductive technology with intracytoplasmic sperm injection in the female partner of the proband.
CONCLUSIONS: This study highlights the identification of a novel homozygous LRRC6 mutation in a consanguineous family and its impact on sperm progressive motility, morphology, and sperm kinetics parameters, which could facilitate the genetic diagnosis of asthenozoospermia and offer valuable perspectives for future genetic counseling endeavors.

Infertility is a prevalent global issue affecting approximately 17.5% of adults, with sole male factor contributing to 20-30% of cases. Oxidative stress (OS) is a critical factor in male infertility, disrupting the balance between reactive oxygen species (ROS) and antioxidants. This imbalance detrimentally affects sperm function and viability, ultimately impairing fertility. OS also triggers molecular changes in sperm, including DNA damage, lipid peroxidation, and alterations in protein expression, further compromising sperm functionality and potential fertilization. Diagnostic tools discussed in this review offer insights into OS markers, antioxidant levels, and intracellular ROS concentrations. By accurately assessing these parameters, clinicians can diagnose male infertility more effectively and thus tailor treatment plans to individual patients. Additionally, this review explores various treatment options for males with OS-associated infertility, such as empirical drugs, antioxidants, nanoantioxidants, and lifestyle modifications. By addressing the root causes of male infertility and implementing targeted interventions, clinicians can optimize treatment outcomes and enhance the chances of conception for couples struggling with infertility.

Oxidative stress (OS) affects men\'s health and impairs spermatogenesis. Micronutrient antioxidants are available for male infertility as complemental support; however, their efficacy remains debatable. This study aimed to investigate whether antioxidants can help to reduce sperm OS and improve semen analysis and quality. We included 171 male partners of couples planning to undergo assisted reproductive technology (ART). Male partners, aged 29-41 years, of couples intending to conceive were self-selected to take daily antioxidants (n = 84) containing folic acid and zinc, or not to take antioxidants (n = 52) for 6 months. We analyzed the alterations in serum oxidant levels, sperm parameters, OS, and deoxyribonucleic acid fragmentation after 3 and 6 months. Additionally, implantation, clinical pregnancy, and miscarriage rates after vitrified-warmed embryo transfer were compared between those taking antioxidants and those not taking them after 6 months. In men with high static oxidation-reduction potential (sORP), we observed a significant improvement in sperm concentration and sORP. The high-quality blastocyst rate tended to increase, and implantation and clinical pregnancy rates also significantly increased after 6 months of intervention. The micronutrient antioxidants could improve sperm function by reducing OS and improving ART outcomes. Therefore, micronutrient antioxidants may be a viable treatment option for male infertility.