Is There a Relevant Clinical Impact in Differentiating Idiopathic versus Unexplained Male Infertility?

Redox Homeostasis and Nrf2-Regulated Mechanisms Are Relevant to Male Infertility

Infertility represents a significant global health challenge, affecting more than 12% of couples worldwide, and most cases of infertility are caused by male factors. Several pathological pathways are implicated in male infertility. The main mechanisms involved are driven by the loss of reduction-oxidation (redox) homeostasis and the resulting oxidative damage as well as the chronic inflammatory process. Increased or severe oxidative stress leads to sperm plasma membrane and DNA oxidative damage, dysregulated RNA processing, and telomere destruction. The signaling pathways of these molecular events are also regulated by Nuclear factor-E2-related factor 2 (Nrf2). The causes of male infertility, the role of oxidative stress in male infertility and the Keap1-Nrf2 antioxidant pathway are reviewed. This review highlights the regulatory role of Nrf2 in the balance between oxidants and antioxidants as relevant mechanisms to male fertility. Nrf2 is involved in the regulation of spermatogenesis and sperm quality. Establishing a link between Nrf2 signaling pathways and the regulation of male fertility provides the basis for molecular modulation of inflammatory processes, reactive oxygen species generation, and the antioxidant molecular network, including the Nrf2-regulated antioxidant response, to improve male reproductive outcomes.

Development of a biomolecular approach to identify sperm functions and fertility using sperm RNAs

Infertility affects a significant percentage of couples worldwide, and male factors contribute significantly to this problem. Traditional assessments of male fertility rely primarily on parameters such as sperm motility, morphology, viability, and concentration. However, these metrics often do not provide a comprehensive understanding of sperm function, which is critical not only for fertilization but also for successful embryo development. Herein, we used porcine spermatozoa as a model to investigate the potential of sperm RNA markers in assessing various aspects of sperm function from motility to fertility. Using artificial insemination, we evaluated male fertility based on the litter size of sows inseminated with sperm from 20 boars. In addition, we measured parameters such as weaning rate, death births, live births, and mummy births. Sperm functional parameters, including motility and kinematics, were assessed before and after in vitro capacitation. Finally, correlations between various sperm functional parameters and sperm RNA markers were explored. Our results revealed interesting relationships between sperm functional parameters. While motility and kinematics were correlated, they were not correlated with sperm capacitation status. Surprisingly, no significant correlations were found between these parameters and male fertility. However, specific parameters of sperm capacitation status after in vitro capacitation were correlated with weaning rate and live births, highlighting their importance in predicting successful fertilization. Further analysis of sperm RNA markers identified genes related to male fertility, including IZUMO1, known for its role in sperm-egg fusion. These genes showed correlations with motility, capacitation, and fertilization parameters, shedding light on their potential roles in sperm function. In conclusion, our study demonstrates that sperm RNA markers hold promise for the diagnosis and prognosis of various aspects of sperm function, providing valuable insights into male infertility. These markers may serve as diagnostic tools to improve our understanding of male fertility problems, ultimately benefiting couples struggling with infertility.

Association of diet and lifestyle factors with semen quality in male partners of Chinese couples preparing for pregnancy

BACKGROUND

Semen quality significantly influences conception, and its preservation is crucial for couples seeking pregnancy. We investigated dietary and lifestyle risk factors impacting semen quality.

METHODS

A total of 466 males from the Guangzhou Women and Children's Medical Center's pre-pregnancy consultation clinic were recruited between January 2021 and March 2023 for inclusion. Semen analysis was performed, and diet and lifestyle data were gathered via questionnaire. Logistic regression was utilized to examine the link between diet, lifestyle variables, and semen quality.

RESULTS

Smoking worsened progressive sperm motility (38.0% vs. 36.0%, t = 2.262; P = 0.049). Alcohol consumption impaired progressive motility (40.5 ± 17.8% vs. 34.7 ± 16.1%, t = 3.396; P < 0.001) and total motility (56.0% vs. 64.0%; P = 0.001). Using plastic beverage bottles for oil or seasonings lowered sperm concentrations (40.4% vs. 59.0% vs. 65.5%; P = 0.032). A sweet diet correlated with higher total sperm motility (55.0% vs. 60.0%, 62.0% vs. 63.2%; P = 0.017). Higher milk product intake improved sperm concentration (41.6106 vs. 63.7106 vs. 66.1*106; P = 0.021) and motility (54.5% vs. 56.0% vs. 63.0%; P = 0.033). More frequent egg consumption increased semen volume (3.1 mL vs. 3.8 mL vs. 4.0 mL; P = 0.038). Roughage intake enhanced sperm concentration (160.8106 vs. 224.6106; P = 0.027), and adequate sleep improved progressive sperm motility rate (35.4% ± 18.2% vs. 40.2 ± 16.3%, F = 3.747; P = 0.024) and total motility (52.7% vs. 61.5%; P = 0.013). The regression model showed that using plastic containers for condiments was a protective factor for semen volume (OR: 0.12; CI 0.03-0.55; P = 0.006), sperm concentration (OR: 0.001, CI 0.00-0.30; P = 0.012), and count (OR: 0.12, CI 0.03-0.48; P = 0.003). Milk and egg consumption were also protective for semen volume (OR: 0.18, CI 0.06-0.51; P = 0.001 and OR: 0.11, CI 0.03-0.55; P = 0.006, respectively), while sufficient sleep benefitted total sperm motility (OR: 0.47, CI 0.24-0.95; P = 0.034).

CONCLUSIONS

Smoking and drinking, type of condiment container, diet preference, sleep duration, and milk, roughage, and egg consumption may reduce semen quality.

Seminal plasma untargeted metabolomic and lipidomic profiling for the identification of a novel panel of biomarkers and therapeutic targets related to male infertility

Male infertility occurs approximately in about 50% of all infertility cases and represents a serious concern worldwide. Traditional semen analysis alone is insufficient to diagnose male infertility. Over the past two decades, advances in omics technologies have led to the widespread application of metabolomics profiling as a valuable diagnostic tool for various diseases and disorders. Seminal plasma represents a rich and easily accessible source of metabolites surrounding spermatozoa, a milieu that provides several indispensable nutrients to sustain sperm motility and fertilization. Changes of metabolic profiles in seminal plasma reflect male reproductive tract disorders. Here, we performed seminal plasma metabolomics and lipidomics profiling to identify a new pattern of biomarkers of male infertility. Seminal plasma samples from unfertile subjects (n = 31) and fertile controls (n = 19) were analyzed using an untargeted metabolomics/lipidomics integrated approach, based on Ultra-High-Pressure Liquid Chromatography-tandem Mass Spectrometry. Partial Least Squares-Discriminant Analysis showed a distinct separation between healthy fertile men and infertile subjects. Among the 15 selected candidate biomarkers based on Variable Importance in Projection scores, phosphatidylethanolamine (PE) (18:1; 18:1) resulted with the highest score. In total, 40 molecular species showed statistically significant variations between fertile and infertile men. Heat-map and volcano plot analysis indicated that acylcarnitines, phosphatidylserine (PS) (40:2) and lactate were decreased, while PE (18:1; 18:1), Phosphatidic acid (PA) (O-19:2; 18:1), Lysophosphatidylethanolamine (LPE) (O-16:1) and Phosphatidylcholine (PC) (O-16:2; 18:1)-CH3 were increased in the infertile group. The present study is the first one to analyze the metabolomics/lipidomics dysregulation in seminal plasma between fertile and infertile individuals regardless of sub-infertility condition. Association of several metabolites/lipids dysregulation with male infertility reinforced data of previous studies performed with different approaches. In particular, we confirmed significantly decreased levels of PS and carnitines in infertile patients as well as the positive correlation with sperm motility and morphology. If validated on a larger prospective cohort, the metabolite biomarkers of infertility in seminal plasma we identified in the present study might inform novel strategies for diagnosis and interventions to overcome male infertility.

Association of living environmental and occupational factors with semen quality in chinese men: a cross-sectional study

Sperm quality can be easily influenced by living environmental and occupational factors. This study aimed to discover potential semen quality related living environmental and occupational factors, expand knowledge of risk factors for semen quality, strengthen men's awareness of protecting their own fertility and assist the clinicians to judge the patient's fertility. 465 men without obese or underweight (18.5 < BMI < 28.5 kg/m2), long-term medical history and history of drug use, were recruited between June 2020 to July 2021, they are in reproductive age (25 < age < 45 years). We have collected their semen analysis results and clinical information. Logistic regression was applied to evaluate the association of semen quality with different factors. We found that living environment close to high voltage line (283.4 × 106/ml vs 219.8 × 106/ml, Cohen d = 0.116, P = 0.030) and substation (309.1 × 106/ml vs 222.4 × 106/ml, Cohen d = 0.085, P = 0.015) will influence sperm count. Experienced decoration in the past 6 months was a significant factor to sperm count (194.2 × 106/ml vs 261.0 × 106/ml, Cohen d = 0.120, P = 0.025). Living close to chemical plant will affect semen PH (7.5 vs 7.2, Cohen d = 0.181, P = 0.001). Domicile close to a power distribution room will affect progressive sperm motility (37.0% vs 34.0%, F = 4.773, Cohen d = 0.033, P = 0.030). Using computers will affect both progressive motility sperm (36.0% vs 28.1%, t = 2.762, Cohen d = 0.033, P = 0.006) and sperm total motility (57.0% vs 41.0%, Cohen d = 0.178, P = 0.009). After adjust for potential confounding factors (age and BMI), our regression model reveals that living close to high voltage line is a risk factor for sperm concentration (Adjusted OR 4.03, 95% CI 1.15-14.18, R2 = 0.048, P = 0.030), living close to Chemical plants is a protective factor for sperm concentration (Adjusted OR 0.15, 95% CI 0.05-0.46, R2 = 0.048, P = 0.001) and total sperm count (Adjusted OR 0.36, 95% CI 0.13-0.99, R2 = 0.026, P = 0.049). Time spends on computer will affect sperm total motility (Adjusted OR 2.29, 95% CI 1.11-4.73, R2 = 0.041, P = 0.025). Sum up, our results suggested that computer using, living and working surroundings (voltage line, substation and chemical plants, transformer room), and housing decoration may association with low semen quality. Suggesting that some easily ignored factors may affect male reproductive ability. Couples trying to become pregnant should try to avoid exposure to associated risk factors. The specific mechanism of risk factors affecting male reproductive ability remains to be elucidated.

Isochromosome 12p Formation Regulates Vitamin D Metabolism in Testicular Cancer

Isochromosome 12p (iChr12p) is typical in almost all invasive testicular cancers. Increased copy number of genes on 12p is associated with the development of a clinically manifest tumor; however, the causative genes have not yet been identified. Chromosome 12 harbors many genes involved in Vitamin D metabolism. RNAseq analysis of Vitamin D receptor (VDR) genes from the TCGA cohort revealed that clustering of VDR expression signatures could differentiate between pure seminomas and non-seminomatous germ cell tumors (NSGCT). Using TCGA mRNA expression of anabolic (CYP2R1, CYP27A1 and CYP27B1) and catabolic (CYP24A1) Vitamin D enzymes, positive (PTHLH, IFNG, and TNF) and negative (FGF23) feedback regulators could also clearly distinguish between pure seminomas and NSGCT. We hypothesize that the regulation of Vitamin D metabolism might be disturbed through iChr12p formation, influencing testicular carcinogenesis via increased FGF23 and PTHLH expression. While FGF23 represses CYP27B1 and activates catabolism of active hormone, increased PTHLH secretion can lead to hypercalcemia via inactivation of VDR. In conclusion, testicular cancer is associated with extensive modifications in intratesticular Vitamin D homeostasis. Further research is needed to clarify whether Vitamin D deficiency causes the formation of iChr12p and whether Vitamin D deficiency via iChr12p genomic aberration is involved in testicular carcinogenesis.

Long-Term Follow-Up after Testicular Torsion: Prospective Evaluation of Endocrine and Exocrine Testicular Function, Fertility, Oxidative Stress and Erectile Function

Background: This study investigates endocrine and exocrine testicular function, oxidative stress (OS) in semen, and erectile function in patients who underwent surgery for suspected testicular torsion (TT). Methods: We evaluated 49 patients over a mean follow-up of 101 months: n = 25 patients treated with surgical exploration, n = 20 patients treated with detorsion, and n = 4 treated with orchiectomy. We performed semen analysis including Male infertility Oxidative System (MyOxSIS) analysis, physical examination, and evaluation of endocrine and erectile function. Results: OS, erectile function and spermiogram categories did not differ significantly between the groups. The interval from the onset of symptoms to surgery differed significantly between groups (p < 0.001). Preservation of the testes was associated with a higher round cell count (p = 0.002) and follicle stimulating hormone (FSH, p = 0.003). OS showed a significant positive correlation with the spermiogram category (0.337; p = 0.022). A negative correlation was observed between OS and age (p = 0.033), sperm concentration (p < 0.001) and total sperm count (p = 0.006). Conclusions: Endocrine, exocrine and erectile function are not significantly affected by TT in the long term. Orchiectomy results in elevated FSH and a lower round cell count compared to preservation of the testis.