Spermatozoa have a highly complex RNA profile. Several of these transcripts are suggested as biomarkers for male infertility and contribute to early development. To analyze the differences between sperm RNA quantity and expression of protamine ( PRM1 and PRM2 ) and testis-specific histone 2B ( TH2B ) genes, spermatozoa from 33 patients who enrolled in assisted reproduction treatment (ART) program were analyzed. Sperm RNA of teratozoospermic (T), oligoteratozoospermic (OT), and normozoospermic (N) samples was extracted, and the differences in transcript levels among the study groups were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR). The correlations of total RNA per spermatozoon and the expression of the transcripts were evaluated in relation to sperm characteristics and preimplantation embryo development. The mean (±standard deviation) RNA amount per spermatozoon was 28.48 (±23.03) femtogram in the overall group and was significantly higher in the OT group than that in N and T groups. Total sperm RNA and gene expression of PRM1 and PRM2 genes were related to preimplantation embryo development and developmental arrest. Specific sperm characteristics were correlated with the expressions of PRM1 , PRM2 , or TH2B genes. We conclude that the sperm RNA amount and composition are important factors and might influence early embryonic development and also differ in different cases of male infertility.
Male ; Humans ; Protamines/metabolism* ; Spermatozoa/metabolism* ; Embryonic Development/genetics* ; Adult ; RNA/genetics* ; Histones/genetics* ; Infertility, Male/genetics* ; Teratozoospermia/genetics* ; Oligospermia/genetics*

Varicocele, the most common and treatable cause of male infertility, significantly impacts fertility. The pathophysiological mechanisms of varicocele have not been fully understood yet. Recent studies have focused on the pathophysiology of varicocele-induced infertility, highlighting inflammation and oxidative stress as key contributing factors. We reviewed recent research on the roles of inflammation and oxidative stress in the pathophysiology of varicocele and found that they negatively impact semen parameters, spermatogenesis, and testicular and epididymal function. In addition, this article summarizes the related factors of inflammation and oxidative stress caused by varicocele. Finally, a brief consideration on the treatments to address inflammation and oxidative stress is proposed. This review may provide treatment options and targets for varicocele-induced infertility. However, the relationship between inflammation and oxidative stress in varicocele still needs further study.
Varicocele/physiopathology* ; Humans ; Oxidative Stress/physiology* ; Infertility, Male/metabolism* ; Male ; Inflammation/physiopathology* ; Spermatogenesis/physiology*

Insulin-like growth factor 2 (IGF2) is a critical endocrine mediator implicated in male reproductive physiology. To investigate the correlation between IGF2 protein levels and various aspects of male infertility, specifically focusing on sperm quality, inflammation, and DNA damage, a cohort of 320 male participants was recruited from the Women's Hospital, Zhejiang University School of Medicine (Hangzhou, China) between 1 st January 2024 and 1 st March 2024. The relationship between IGF2 protein concentrations and sperm parameters was assessed, and Spearman correlation and linear regression analysis were employed to evaluate the independent associations between IGF2 protein levels and risk factors for infertility. Enzyme-linked immunosorbent assay (ELISA) was used to measure IGF2 protein levels in seminal plasma, alongside markers of inflammation (tumor necrosis factor-alpha [TNF-α] and interleukin-1β [IL-1β]). The relationship between seminal plasma IGF2 protein levels and DNA damage marker phosphorylated histone H2AX (γ-H2AX) was also explored. Our findings reveal that IGF2 protein expression decreased notably in patients with asthenospermia and teratospermia. Correlation analysis revealed nuanced associations between IGF2 protein levels and specific sperm parameters, and low IGF2 protein concentrations correlated with increased inflammation and DNA damage in sperm. The observed correlations between IGF2 protein levels and specific sperm parameters, along with its connection to inflammation and DNA damage, underscore the importance of IGF2 in the broader context of male reproductive health. These findings lay the groundwork for future research and potential therapeutic interventions targeting IGF2-related pathways to enhance male fertility.
Humans ; Male ; Insulin-Like Growth Factor II/metabolism* ; Infertility, Male/genetics* ; DNA Damage ; Adult ; Inflammation/metabolism* ; Spermatozoa/metabolism* ; Semen Analysis ; Semen/metabolism* ; Tumor Necrosis Factor-alpha/metabolism* ; Histones/metabolism* ; Interleukin-1beta/metabolism*

Reactive oxygen species (ROS) play a dual role in mammalian spermatozoa. At high levels, they are detrimental to sperm function since they can promote oxidative stress that produces oxidation of protein, lipids, and sperm DNA. This oxidative damage is associated with male infertility. On the other hand, when ROS are produced at low levels, they participate in the redox signaling necessary for sperm capacitation. Capacitation-associated ROS are produced by the sperm oxidase, whose identity is still elusive, located in the plasma membrane of the spermatozoon. ROS, such as superoxide anion, hydrogen peroxide, nitric oxide, and peroxynitrite, activate protein kinases and inactivate protein phosphatases with the net increase of specific phosphorylation events. Peroxiredoxins (PRDXs), antioxidant enzymes that fight against oxidative stress, regulate redox signaling during capacitation. Among them, PRDX6, which possesses peroxidase and calcium-independent phospholipase A 2 (iPLA 2 ) activities, is the primary regulator of redox signaling and the antioxidant response in human spermatozoa. The lysophosphatidic acid signaling is essential to maintain sperm viability by activating the phosphatidylinositol 3-kinase/protein kinase (PI3K/AKT) pathway, and it is regulated by PRDX6 iPLA 2 , protein kinase C (PKC), and receptor-type protein tyrosine kinase. The understanding of redox signaling is crucial to pave the way for novel diagnostic tools and treatments of male infertility.
Humans ; Male ; Spermatozoa/physiology* ; Signal Transduction/physiology* ; Oxidation-Reduction ; Peroxiredoxins/physiology* ; Reactive Oxygen Species/metabolism* ; Oxidative Stress/physiology* ; Sperm Capacitation/physiology* ; Infertility, Male/metabolism*

The circadian clock is an important internal time regulatory system for a range of physiological and behavioral rhythms within living organisms. Testosterone, as one of the most critical sex hormones, is essential for the development of the reproductive system, maintenance of reproductive function, and the overall health of males. The secretion of testosterone in mammals is characterized by distinct circadian rhythms and is closely associated with the regulation of circadian clock genes. Here we review the central and peripheral regulatory mechanisms underlying the influence of circadian clock genes upon testosterone synthesis. We also examined the specific effects of these genes on the occurrence, development, and treatment of common male diseases, including late-onset hypogonadism, erectile dysfunction, male infertility, and prostate cancer.
Testosterone/metabolism* ; Humans ; Male ; Circadian Clocks/genetics* ; Circadian Rhythm Signaling Peptides and Proteins/metabolism* ; Circadian Rhythm/physiology* ; Hypogonadism/metabolism* ; Erectile Dysfunction/metabolism* ; Infertility, Male/metabolism* ; Prostatic Neoplasms/metabolism* ; Men's Health

Varicocele (VC) is a common cause of male infertility, yet there is a lack of molecular information for VC-associated male infertility. This study investigated alterations in the seminal plasma metabolomic and lipidomic profiles of infertile male VC patients. Twenty infertile males with VC and twenty-three age-matched healthy controls (HCs) were recruited from Peking Union Medical College Hospital (Beijing, China) between October 2019 and April 2021. Untargeted metabolite and lipid profiles from seminal plasma were analyzed using mass spectrometry. Four hundred and seventy-six metabolites and seventeen lipids were significantly different in infertile male VC patients compared to HCs. The top enriched pathways among these significantly different metabolites are protein digestion and absorption, aminoacyl-transfer RNA (tRNA) biosynthesis, and biosynthesis of amino acids. Different key lipid species, including triglyceride (TG), diacylglycerol (DG), ceramides (Cer), and phosphatidylserine (PS), varied between VC and HC groups. The distinct metabolites and lipids were moderately correlated. DL-3-phenyllactic acid is a potential diagnostic biomarker for VC-related male infertility (area under the curve [AUC] = 0.893), positively correlating with sperm count, concentration, and motility. Furthermore, DL-3-phenyllactic acid is the only metabolite shared by all four comparisons (VC vs HC, VC-induced oligoasthenospermia [OAS] vs VC-induced asthenospermia [AS], OAS vs HC, and AS vs HC). DL-3-phenyllactic acid significantly decreased in OAS than AS. Metabolite-targeting gene analysis revealed carbonic anhydrase 9 (CA9) might be the strongest candidate associated with the onset and severity of VC. The seminal plasma metabolite and lipid profiles of infertile males with VC differ significantly from those of HCs. DL-3-phenyllactic acid could be a promising biomarker.
Humans ; Male ; Varicocele/complications* ; Infertility, Male/etiology* ; Semen/metabolism* ; Lipidomics ; Adult ; Metabolomics ; Case-Control Studies ; Biomarkers/metabolism*

OBJECTIVE: To explore the role of reactive oxygen species (ROS) and lactate dehydrogenase isoenzyme X (LDH-X) in the changes of sperm mitochondrial membrane potential (MMP) in infertility patients with varicocele (VC). METHODS: This study included 38 infertility patients with VC (VCinf), 35 non-VC infertile males (NVCinf), and 30 normal fertile men as controls. We obtained the routine semen parameters using the sperm quality analysis system, examined the contents of LDH-X in the seminal plasma and sperm with the automatic biochemical analyzer, measured the level of malondialdehyde (MDA) in seminal plasma by thiobarbituric acid (TBA) colorimetry, and determined the expressions of mitochondrial membrane potential (MMP) and LDH-X mRNA in the sperm using JC-1 fluorescence probe and RT-PCR. RESULTS: No statistically significant differences were observed among the three groups of subjects in age, semen pH value, semen volume and sperm concentration (P > 0.05). Compared with the normal fertile controls, the patients in the VCinf and NVCinf groups showed significantly decreased sperm motility (［52.36 ± 12.48］% vs ［34.74 ± 15.23］% vs ［25.76 ± 13.73］%, P< 0.05), percentage of progressively motile sperm (PMS) (［42.54 ± 13.58］% vs ［29.10 ± 14.17］% vs ［20.95 ± 12.33］%, P< 0.05), sperm LDH-X (［16.46 ± 5.47］ vs ［13.63 ± 4.50］ vs ［10.18 ± 3.00］ mU/106, P< 0.05), sperm MMP (［48.04 ± 11.62］% vs ［40.86 ± 12.69］% vs ［34.41 ± 13.93］%, P< 0.05) and expression of sperm LDH-X mRNA (P< 0.05). but increased seminal plasma LDH-X (［935.36 ± 229.48］ vs ［1241.05 ± 337.07］ vs ［1425.08 ± 469.35］ U/L, P< 0.05), seminal plasma/whole sperm LDH-X (［1.06 ± 0.35］ vs ［1.40 ± 0.34］ vs ［1.63 ± 0.66］, P< 0.05), and content of seminal plasma MDA (［1.10 ± 0.19］ vs ［1.59 ± 0.27］ vs ［2.00 ± 0.22］ nmol/ml, P< 0.05). CONCLUSION Excessive ROS in the reproductive system of VCinf patients reduces the content of MMP and causes the overflow of LDH-X out of sperm cells. Therefore the decrease of sperm LDH-X may be accompanied by that of MMP.
Humans ; Male ; Infertility, Male/etiology* ; Varicocele/metabolism* ; Adult ; Reactive Oxygen Species/metabolism* ; Spermatozoa/metabolism* ; L-Lactate Dehydrogenase/metabolism* ; Membrane Potential, Mitochondrial ; Isoenzymes/metabolism* ; Case-Control Studies ; Young Adult ; Mitochondrial Membranes/metabolism*

Male infertility has become a global concern, accounting for 20-70% of infertility. Dysfunctional spermatogenesis is the most common cause of male infertility; thus, treating abnormal spermatogenesis may improve male infertility and has attracted the attention of the medical community. Mitochondria are essential organelles that maintain cell homeostasis and normal physiological functions in various ways, such as mitochondrial oxidative phosphorylation (OXPHOS). Mitochondrial OXPHOS transmits electrons through the respiratory chain, synthesizes adenosine triphosphate (ATP), and produces reactive oxygen species (ROS). These mechanisms are vital for spermatogenesis, especially to maintain the normal function of testicular Sertoli cells and germ cells. The disruption of mitochondrial OXPHOS caused by external factors can result in inadequate cellular energy supply, oxidative stress, apoptosis, or ferroptosis, all inhibiting spermatogenesis and damaging the male reproductive system, leading to male infertility. This article summarizes the latest pathological mechanism of mitochondrial OXPHOS disorder in testicular Sertoli cells and germ cells, which disrupts spermatogenesis and results in male infertility. In addition, we also briefly outline the current treatment of spermatogenic malfunction caused by mitochondrial OXPHOS disorders. However, relevant treatments have not been fully elucidated. Therefore, targeting mitochondrial OXPHOS disorders in Sertoli cells and germ cells is a research direction worthy of attention. We believe this review will provide new and more accurate ideas for treating male infertility.
Male ; Humans ; Infertility, Male/metabolism* ; Oxidative Phosphorylation ; Mitochondria/metabolism* ; Spermatogenesis/physiology* ; Sertoli Cells/metabolism* ; Oxidative Stress/physiology* ; Animals ; Reactive Oxygen Species/metabolism*

Male reproductive infections are known to shape the immunological homeostasis of the testes, leading to male infertility. However, the specific pathogenesis of these changes remains poorly understood. Exosomes released in the inflammatory microenvironment are important in communication between the local microenvironment and recipient cells. Here, we aim to identify the immunomodulatory properties of inflammatory testes-derived exosomes (IT-exos) and explore their underlying mechanisms in orchitis. IT-exos were isolated using a uropathogenic Escherichia coli (UPEC)-induced orchitis model and confirmed that IT-exos promoted proinflammatory M1 activation with increasing expression of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) in vitro. We further used small RNA sequencing to identify the differential miRNA profiles in exosomes and primary testicular macrophages (TMs) from normal and UPEC-infected testes, respectively, and identified that miR-155-5p was highly enriched in IT-exos and TMs from inflammatory testes. Further study of bone marrow derived macrophages (BMDMs) transfected with miR-155-5p mimic showed that macrophages polarized to proinflammatory phenotype. In addition, the mice that were administrated IT-exos showed remarkable activation of TM1-like macrophages; however, IT-exos with silencing miR-155-5p showed a decrease in proinflammatory responses. Overall, we demonstrate that miR-155-5p delivered by IT-exos plays an important role in the activation of TM1 in UPEC-induced orchitis. Our study provides a new perspective on the immunological mechanisms underlying inflammation-related male infertility.
Humans ; Male ; Mice ; Animals ; Orchitis ; Uropathogenic Escherichia coli/metabolism* ; MicroRNAs/metabolism* ; Exosomes/metabolism* ; Macrophages/metabolism* ; Phenotype ; Infertility, Male/metabolism*

Teratozoospermia is a rare disease associated with male infertility. Several recurrent genetic mutations have been reported to be associated with abnormal sperm morphology, but the genetic basis of tapered-head sperm is not well understood. In this study, whole-exome sequencing (WES) identified a homozygous WD repeat domain 12 (WDR12; p.Ser162Ala/c.484T>G) variant in an infertile patient with tapered-head spermatozoa from a consanguineous Chinese family. Bioinformatic analysis predicted this mutation to be a pathogenic variant. To verify the effect of this variant, we analyzed WDR12 protein expression in spermatozoa of the patient and a control individual, as well as in the 293T cell line, by Western blot analysis, and found that WDR12 expression was significantly downregulated. To understand the role of normal WDR12, we evaluated its mRNA and protein expression in mice at different ages. We observed that WDR12 expression was increased in pachytene spermatocytes, with intense staining visible in round spermatid nuclei. Based on these results, the data suggest that the rare biallelic pathogenic missense variant (p.Ser162Ala/c.484T>G) in the WDR12 gene is associated with tapered-head spermatozoa. In addition, after intracytoplasmic sperm injection (ICSI), a successful pregnancy was achieved. This finding indicates that infertility associated with this WDR12 homozygous mutation can be overcome by ICSI. The present results may provide novel insights into understanding the molecular mechanisms of male infertility.
Humans ; Pregnancy ; Female ; Male ; Animals ; Mice ; Teratozoospermia/pathology* ; Semen/metabolism* ; Infertility, Male/metabolism* ; Spermatozoa/metabolism* ; Mutation ; RNA-Binding Proteins/metabolism* ; Cell Cycle Proteins/genetics*