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*

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*

OBJECTIVE: To explore the effects of electroacupuncture (EA) on pregnancy outcomes after assisted reproduction and mitochondrial function of granulosa cells (GCs) in patients with polycystic ovary syndrome (PCOS) and phlegm-dampness syndrome. METHODS: In this randomized controlled trial, 90 infertile women with PCOS and phlegm-dampness syndrome were recruited between August 2022 and December 2022. Patients were randomly assigned to the EA and control groups using a random sequence of codes in the order of enrolment, with 45 in in each group. Both groups underwent the ovarian stimulation protocol. The patients in the EA group received EA therapy including Zhongwan (CV 12), Qihai (CV 6), bilateral Xuehai (SP 10), Sanyinjiao (SP 6), Yinlingquan (SP 9), Tianshu (ST 25), Zusanli (ST 36), and Fenglong (ST 40), and the patients in the control group was treated with pseudo-acupuncture. The intervention was 25 min twice a week for a total of 6 times until the trigger day after menstruation had ended in the cycle before oocyte retrieval. The primary outcomes were clinical pregnancy rate (CPR) and the number of high-quality embryos. The secondary outcomes were (1) pregnancy-related indicators, including fresh embryo transfer rate (ETR), ovarian hyperstimulation syndrome (OHSS) rate, early pregnancy loss rate (ePLR), ectopic pregnancy rate, live birth rate (LBR), and cumulative CPR; (2) mitochondrial autophagy and mitochondrial membrane potential (MMP) in GCs; and (3) scoring for Chinese medicine syndrome. Adverse events to assess clinical safety were also monitored. RESULTS: The cumulative CPR was significantly higher in the EA group (42/45, 93.3%) than in the control group (38/45, 84.4%, P=0.036). The number of high-quality embryos and fresh ETR in the EA group were higher than those in the control group (3.80±1.65 vs. 2.44±1.34, P<0.001; 46.7% vs 24.4%, P=0.028). Ectopic pregnancies were not observed in either group. There were no significant differences in the fresh CPR, OHSS rate, ePLR or LBR between the two groups (P>0.05). Compared with the control group, the EA group showed lower expression levels of miR-146a-5p mRNA and P62 protein in GCs and higher levels of MMP and the LC3-II/LC3-I protein ratio (all P<0.01). The phlegm-dampness syndrome scores of the EA group were significantly lower than those of the control group (P<0.01). CONCLUSIONS EA significantly improved pregnancy outcomes in patients with PCOS and phlegm dampness syndrome. Mechanistically, this effect may be related to EA in decreasing miR-146a-5p mRNA expression, promoting mitochondrial autophagy in GCs, and improving mitochondrial function, which may contribute to improved oocyte quality. (Trial registration No. ChiCTR2200062915).
Humans ; Female ; Polycystic Ovary Syndrome/therapy* ; Pregnancy ; Electroacupuncture ; Granulosa Cells/metabolism* ; Adult ; Mitochondria/metabolism* ; Pregnancy Outcome ; Pregnancy Rate ; Reproductive Techniques, Assisted ; Infertility, Female/therapy*

OBJECTIVES: Transcervical resection of adhesions (TCRA) under hysteroscopy is the mainstay treatment for intrauterine adhesions (IUA), but its effectiveness varies depending on the surgical approach. This study aims to investigate the impact of different surgical techniques on endometrial repair and pregnancy outcomes in patients with secondary infertility and moderate-to-severe IUA. METHODS: A retrospective analysis was conducted on 225 patients who underwent TCRA followed by in vitro fertilization and embryo transfer between January 2021 and December 2022. Patients were grouped based on the surgical method: A cold knife group (n=127) and an electrosurgical group (n=98). Adhesions were separated using either cold knife or electrosurgical instruments. Postoperative visualization of uterine angle and tubal ostia, endometrial restoration, vascular endothelial growth factor (VEGF) expression in adhesion tissues, and clinical pregnancy outcomes were compared. Univariate and multivariate Logistic regression analyses were performed to identify factors influencing pregnancy outcomes. A LightGBM model was constructed to predict pregnancy outcomes. RESULTS: Compared with the electrosurgical group, patients in the cold knife group had significantly greater postoperative endometrial thickness [(8.86±0.53) mm vs (8.10±0.87) mm, P<0.05], higher live birth rates (64.57% vs 30.61%, P<0.05), and lower VEGF expression (1.31±0.09 vs 1.53±0.16, P<0.05). Logistic regression analyses identified age, number of visible tubal ostia postoperatively, and surgical method as significant factors affecting pregnancy outcomes (P<0.05). The LightGBM model based on surgical method had an area under the curve (AUC) of 0.882 (0.838-0.926), with internal validation AUC of 0.817 (0.790-0.840). CONCLUSIONS Cold knife surgery promotes faster recovery of the endometrial microenvironment and earlier improvement of fertility in patients with secondary infertility and IUA Surgical method is a key factor influencing pregnancy outcomes, and the LightGBM model based on surgical approach shows good predictive performance for pregnancy outcomes in patients with moderate-to-severe IUA.
Humans ; Female ; Pregnancy ; Tissue Adhesions/surgery* ; Retrospective Studies ; Adult ; Pregnancy Outcome ; Uterine Diseases/surgery* ; Hysteroscopy/methods* ; Infertility, Female/etiology* ; Electrosurgery/methods* ; Fertilization in Vitro ; Endometrium/surgery* ; Embryo Transfer ; Vascular Endothelial Growth Factor A/metabolism*