Correlation of genetic results with testicular histology, hormones and sperm retrieval in nonobstructive azoospermia patients with testis biopsy

Characteristics of gut microbiota in patients with asthenozoospermia: a Chinese pilot study

BACKGROUND

Identification of intestinal flora composition is significant for exploring the cause and pathogenic mechanisms of the gut-testis axis and clarifying the relationship between microbiota and infertility. Our study aimed to examine the alternation in gut microbiota composition and identify potential microbes associated with development of Asthenozoospermia (AS).

METHOD

A total of 580 males were recruited in the outpatient department of Tianjin Medical University General Hospital between September 2021 and March 2023. Sperm parameters were analyzed according to the WHO laboratory manual. The 16 S rRNA gene high-throughput sequencing was performed to detect the gut microbiota composition in fecal samples. LEfSe analysis was used to screen key microbiota. PICRUSt2 software was utilized to predict relevant pathways.

RESULTS

After rigorous screening, 60 isolated AS patients (AS group) and 48 healthy men (NC group) were enrolled. No significant differences were observed in demographic characteristics (p > 0.05), semen volume (p = 0.718), sperm concentration (p = 0.109), or total sperm count (p = 0.200). Sperm total motility and progressive motility were significantly decreased in the AS group (p < 0.001). AS patients had significantly lower alpha diversity indices (Chao1, observed OTUs, and PD Whole-tree; p < 0.05). The beta-diversity of gut microbiota in AS patients significantly differed from NC men (PCoA analysis, p = 0.001). Firmicutes, Bacteroidota, Proteobacteria, and Actinobacteria were the primary phyla, with the dominant genera including Bacteroides, Prevotella, and Blautia. Eleven key genera such as Escherichia_Shigella and Prevotellaceae_UCG_001 were identified by LEfSe analysis. Most of these genera were negatively correlated with sperm mobility. Eighty-eight KEGG pathways, including steroid biosynthesis and meiosis, were significantly enriched between the two groups.

CONCLUSIONS

It appears that gut microbiota composition in AS patients significantly differed from that in healthy men, and the development of AS might be associated with intestinal flora dysbiosis.

Aberrant Gene Expression Profiling in Men With Sertoli Cell-Only Syndrome

Sertoli cell-only syndrome (SCOS) is the most severe and common pathological type of non-obstructive azoospermia. The etiology of SCOS remains largely unknown to date despite a handful of studies reported in this area. According to the gene expression of testicular tissue samples in six datasets from the Gene Expression Omnibus, we detected 1441 differentially expressed genes (DEGs) between SCOS and obstructive azoospermia (OA) testicular tissue samples. Enriched GO terms and KEGG pathways for the downregulated genes included various terms and pathways related to cell cycle and reproduction, while the enrichment for the upregulated genes yielded many inflammation-related terms and pathways. In accordance with the protein-protein interaction (PPI) network, all genes in the most critical module belonged to the downregulated DEGs, and we obtained nine hub genes, including CCNB1, AURKA, CCNA2, BIRC5, TYMS, UBE2C, CDC20, TOP2A, and OIP5. Among these hub genes, six were also found in the most significant SCOS-specific module obtained from consensus module analysis. In addition, most of SCOS-specific modules did not have a consensus counterpart. Based on the downregulated genes, transcription factors (TFs) and kinases within the upstream regulatory network were predicted. Then, we compared the difference in infiltrating levels of immune cells between OA and SCOS samples and found a significantly higher degree of infiltration for most immune cells in SCOS than OA samples. Moreover, CD56bright natural killer cell was significantly associated with six hub genes. Enriched hallmark pathways in SCOS had remarkably more upregulated pathways than the downregulated ones. Collectively, we detected DEGs, significant modules, hub genes, upstream TFs and kinases, enriched downstream pathways, and infiltrated immune cells that might be specifically implicated in the pathogenesis of SCOS. These findings provide new insights into the pathogenesis of SCOS and fuel future advances in its theranostics.

ICSI outcomes for infertile men with severe or complete asthenozoospermia

BACKGROUND

Severe or complete asthenozoospermia is a rare entity that can lead to male infertility. In this study, we explored whether different extents of severe or complete asthenozoospermia could affect intracytoplasmic sperm injection (ICSI) outcomes and compared the ICSI outcomes using testicular spermatozoa with those using ejaculated spermatozoa in couples with complete asthenozoospermia.

RESULTS

Ninety-seven couples with severe or complete asthenozoospermia who underwent ICSI between January 2014 and December 2018 were included. According to the sperm category used in ICSI, patients were categorized into four groups: ejaculated progressive motile sperm group (Ep-group), ejaculated non-progressive motile sperm group (En-group), ejaculated immotile sperm group (Ei-group), and testicular sperm group (TESE-group). We compared the baseline characteristics, hormone profile, semen parameters, normal fertilization, good-quality embryos on day 3, transferred embryos, and ICSI outcomes in the four groups. The clinical pregnancy rate was significantly increased in the Ep-group (65.4%, P = 0.019) and TESE-group (63.6%, P = 0.035) compared with that in the Ei-group (23.1%). The ongoing pregnancy rate in the Ei-group was significantly lower than that in the Ep-group (23.1% vs. 61.5%, P = 0.041). Moreover, the biochemical pregnancy rate, ongoing pregnancy rate, and live birth rate were much lower in the Ei-group than in the TESE-group (30.8% vs. 63.6%, 23.1% vs. 40.4% and 23.1% vs. 40.4%, respectively).

CONCLUSIONS

In couples with complete asthenozoospermia, testicular spermatozoa should be preferred to ejaculated spermatozoa for obtaining a better ICSI outcome. With the appropriate selection of testicular spermatozoa, the extent of severe or complete asthenozoospermia may not affect the ICSI outcomes. Future studies with a larger sample size are warranted to validate these findings.

NBMA Promotes Spermatogenesis by Mediating Oct4 Pathway

Non-obstructive azoospermia is one of the most common causes of male infertility, but there is still no specific treatment drug. Given that the Oct4 (Octamer-binding transcription factor 4) has an important regulatory effect on spermatogenesis, activating it can effectively promote spermatogenesis, so it is of great value to develop Oct4-targeted drug design and elucidating its mechanism of action. Here, we screened out the Oct4-targeted drug molecule NBMA (N-benzyl-4-methoxy-2-(1-(4-(trifluoromethyl)phenyl)vinyl)aniline) by computer-assisted technology, and found that it has a significant promoting effect on spermatogenesis in the established mouse azoospermia model. Subsequently, through transcriptome sequencing and enrichment analysis, real-time fluorescent quantitative PCR (qPCR) and western blot experiments revealed that NBMA promotes the differentiation of spermatogonial stem cells by activating the Oct4 pathway, thereby promoting spermatogenesis. This study proves that NBMA is a molecule with great potential to be developed as a therapeutic drug for azoospermia. It also shows that computer-assisted, chemical and biological multidisciplinary methods play a very important role in innovative drug discovery.

Potential Pathogenic Bacteria in Seminal Microbiota of Patients with Different Types of Dysspermatism

Human microbiota play an important role in the health of their human hosts. Recent studies have demonstrated that microbiota exist in seminal plasma. The current study aims to elucidate whether seminal microbiota exist in patients with different types of dysspermatism and whether bacterial biomarkers can be identified for them. A total of 159 study participants were recruited, including 22 patients with oligoasthenospermia, 58 patients with asthenospermia, 8 patients with azoospermia, 13 patients with oligospermia, and 58 matched healthy controls. Seminal microbiota composition was analyzed using 16S rRNA gene-based sequencing. The results showed that the composition of seminal microbiota of patients with dysspermatism differed from those of healthy controls. Comparison of the microbiota composition in semen samples from patients with different types of dysspermatism showed that microbiota in patients with asthenospermia and oligoasthenospermia were distinct from healthy controls in beta diversity (P < 0.05). Characteristic biomarkers, including Ureaplasma, Bacteroides, Anaerococcus, Finegoldia, Lactobacillus and Acinetobacter lwoffii, were identified based on LEfSe analysis. Inferred functional analysis based on seminal microbiome data further indicated the presence of potential pathogenic biomarkers in patients with asthenospermia and oligoasthenospermia. These results provided profiles of seminal microbiota exhibited in different types of dysspermatism, thus providing new insights into their pathogenesis.

Mechanisms of the Testis Toxicity Induced by Chronic Exposure to Mequindox

Mequindox (MEQ) is a synthetic antimicrobial agent widely used in China since the 1980s. Although the toxicity of MEQ is well recognized, its testis toxicity has not been adequately investigated. In the present study, we provide evidence that MEQ triggers oxidative stress, mitochondrion dysfunction and spermatogenesis deficiency in mice after exposure to MEQ (0, 25, 55, and 110 mg/kg in the diet) for up to 18 months. The genotoxicity and adrenal toxicity may contribute to sperm abnormalities caused by MEQ. Moreover, using LC/MS-IT-TOF analysis, two metabolites, 3-methyl-2-(1-hydroxyethyl) quinoxaline-N4-monoxide (M4) and 3-methyl-2-(1-hydroxyethyl) quinoxaline-N1-monoxide (M8), were detected in the serum of mice, which directly confirms the relationship between the N→O group reduction metabolism of MEQ and oxidative stress. Interestingly, only M4 was detected in the testes, suggesting that the higher reproductive toxicity of M4 than M8 might be due to the increased stability of M4-radical (M4-R) compared to M8-radical (M8-R). Furthermore, the expression of the blood-testis barrier (BTB)-associated junctions such as tight junctions, gap junctions and basal ectoplasmic specializations were also examined. The present study demonstrated for the first time the role of the M4 in testis toxicity, and illustrated that the oxidative stress, mitochondrion dysfunction and interference in spermatogenesis, as well as the altered expression of BTB related junctions, were involved in the reproductive toxicity mediated by MEQ in vivo.

Toxic metabolites, Sertoli cells and Y chromosome related genes are potentially linked to the reproductive toxicity induced by mequindox

Mequindox (MEQ) is a relatively new synthetic antibacterial agent widely applied in China since the 1980s. However, its reproductive toxicity has not been adequately performed. In the present study, four groups of male Kunming mice (10 mice/group) were fed diets containing MEQ (0, 25, 55 and 110 mg/kg in the diet) for up to 18 months. The results show that M4 could pass through the blood-testis barrier (BTB), and demonstrate that Sertoli cells (SCs) are the main toxic target for MEQ to induce spermatogenesis deficiency. Furthermore, adrenal toxicity, adverse effects on the hypothalamic-pituitary-testicular axis (HPTA) and Leydig cells, as well as the expression of genes related to steroid biosynthesis and cholesterol transport, were responsible for the alterations in sex hormones in the serum of male mice after exposure to MEQ. Additionally, the changed levels of Y chromosome microdeletion related genes, such as DDX3Y, HSF2, Sly and Ssty2 in the testis might be a mechanism for the inhibition of spermatogenesis induced by MEQ. The present study illustrates for the first time the toxic metabolites of MEQ in testis of mice, and suggests that SCs, sex hormones and Y chromosome microdeletion genes are involved in reproductive toxicity mediated by MEQ in vivo.