Evaluation of immune status in testis and macrophage polarization associated with testicular damage in patients with nonobstructive azoospermia

Impaired Spermatogenesis in Infertile Patients with Orchitis and Experimental Autoimmune Orchitis in Rats

Experimental autoimmune orchitis (EAO) is a well-established rodent model of organ-specific autoimmunity associated with infertility in which the testis immunohistopathology has been extensively studied. In contrast, analysis of testis biopsies from infertile patients associated with inflammation has been more limited. In this work, testicular biopsies from patients with idiopathic non-obstructive azoospermia diagnosed with hypospermatogenesis (HypoSp) [mild: n = 9, and severe: n = 11], with obstructive azoospermia and complete Sp (spermatogenesis) (control group, C, n = 9), and from Sertoli cell-only syndrome (SCOS, n = 9) were analyzed for the presence of immune cells, spermatogonia and Sertoli cell (SCs) alterations, and reproductive hormones levels. These parameters were compared with those obtained in rats with EAO. The presence of increased CD45+ cells in the seminiferous tubules (STs) wall and lumen in severe HypoSp is associated with increased numbers of apoptotic meiotic germ cells and decreased populations of undifferentiated and differentiated spermatogonia. The SCs showed an immature profile with the highest expression of AMH in patients with SCOS and severe HypoSp. In SCOS patients, the amount of SCs/ST and Ki67+ SCs/ST increased and correlated with high serum FSH levels and CD45+ cells. In the severe phase of EAO, immune cell infiltration and apoptosis of meiotic germ cells increased and the number of undifferentiated and differentiated spermatogonia was lowest, as previously reported. Here, we found that orchitis leads to reduced sperm number, viability, and motility. SCs were mature (AMH-) but increased in number, with Ki67+ observed in severely damaged STs and associated with the highest levels of FSH and inflammatory cells. Our findings demonstrate that in a scenario where a chronic inflammatory process is underway, FSH levels, immune cell infiltration, and immature phenotypes of SCs are associated with severe changes in spermatogenesis, leading to azoospermia. Furthermore, AMH and Ki67 expression in SCs is a distinctive marker of severe alterations of STs in human orchitis.

Human Umbilical Cord Mesenchymal Stem Cell-Derived Exosomes Rescue Testicular Aging

BACKGROUND

Testicular aging is associated with diminished fertility and certain age-related ailments, and effective therapeutic interventions remain elusive. Here, we probed the therapeutic efficacy of exosomes derived from human umbilical cord mesenchymal stem cells (hUMSC-Exos) in counteracting testicular aging.

METHODS

We employed a model of 22-month-old mice and administered intratesticular injections of hUMSC-Exos. Comprehensive analyses encompassing immunohistological, transcriptomic, and physiological assessments were conducted to evaluate the effects on testicular aging. Concurrently, we monitored alterations in macrophage polarization and the oxidative stress landscape within the testes. Finally, we performed bioinformatic analysis for miRNAs in hUMSC-Exos.

RESULTS

Our data reveal that hUMSC-Exos administration leads to a marked reduction in aging-associated markers and cellular apoptosis while promoting cellular proliferation in aged testis. Importantly, hUMSC-Exos facilitated the restoration of spermatogenesis and elevated testosterone synthesis in aged mice. Furthermore, hUMSC-Exos could attenuate inflammation by driving the phenotypic shift of macrophages from M1 to M2 and suppress oxidative stress by reduced ROS production. Mechanistically, these efficacies against testicular aging may be mediated by hUMSC-Exos miRNAs.

CONCLUSIONS

Our findings suggest that hUMSC-Exos therapy presents a viable strategy to ameliorate testicular aging, underscoring its potential therapeutic significance in managing testicular aging.

High-fructose consumption suppresses insulin signaling pathway accompanied by activation of macrophage and apoptotic markers in rat testis

Dietary high-fructose may cause metabolic disturbances; however, its effect on the reproductive system is little understood. The insulin signaling pathway is critical in testicular development, maintenance of microcirculation and spermatogenesis. Therefore, in this study, we aimed to investigate the impact of dietary high-fructose on insulin signaling pathway as well as macrophage and apoptotic markers in testicular tissue of rats. Fructose was administered to male Wistar rats as a 20% solution in drinking water for fifteen-week. Gene expression of ir-β, irs-1, irs-2, pi3k, akt, mtor, and enos in the testicular samples was determined by real-time PCR. Protein expression of IR, IRS-1, IRS-2, PI3K, Akt, phospho-Akt (p-Akt), mTOR, eNOS, phospho-eNOS (p-eNOS), and GLUT5 was established by analysis of Western Blot. Testicular expression of occludin, CD163, CD68, caspase-8, and caspase-3 was analyzed by using immunohistochemical assay. Testicular level of fructose was measured by colorimetric method. Dietary high-fructose decreased mRNA expressions of irs-1, irs-2, pi3k, and mtor in the testicular tissue of rats. Also, this dietary intervention impaired protein expressions of IR, IRS-1, IRS-2, PI3K, p-Akt, mTOR, eNOS, and p-eNOS as well as p-Akt/Akt and p-eNOS/eNOS ratios in the testis of rats. However, a high-fructose diet increased the expression of CD163, CD68, caspase-8 and caspase-3, but decreased that of occludin, in the testicular tissue of rats. The high-fructose consumption in rats suppresses testicular insulin signaling but activates macrophages-related factors and apoptotic markers. These changes induced by dietary fructose could be related to male reproductive dysfunction.

Zinc oxide nanoparticles-induced testis damage at single-cell resolution: Depletion of spermatogonia reservoir and disorder of Sertoli cell homeostasis

The widespread application of zinc oxide nanoparticles (ZnO NPs) in our daily life has initiated an enhanced awareness of their biosafety concern. An incredible boom of evidence of organismal disorder has accumulated for ZnO NPs, yet there has been no relevant study at the single-cell level. Here, we profiled > 28,000 single-cell transcriptomes and assayed > 25,000 genes in testicular tissues from two healthy Sprague Dawley (SD) rats and two SD rats orally exposed to ZnO NPs. We identified 10 cell types in the rat testis. ZnO NPs had more deleterious effects on spermatogonia, Sertoli cells, and macrophages than on the other cell types. Cell-cell communication analysis indicated a sharp decrease of interaction intensity for all cell types except macrophages in the ZnO NPs group than in the control group. Interestingly, two distinct maturation states of spermatogonia were detected during pseudotime analysis, and ZnO NPs induced reservoir exhaustion of undifferentiated spermatogonia. Mechanically, ZnO NPs triggered fatty acid accumulation in GC-1 cells through protein kinase B (Akt)/mammalian target of rapamycin (mTOR) signaling and peroxisome proliferator-activated receptor alpha (PPARα)/acyl-CoA oxidase 1 (Acox1) axis, contributing to cell apoptosis. In terms of Sertoli cells, downregulated genes were highly enriched for tight junction. In vitro and in vivo experiments verified that ZnO NPs disrupted blood-testis barrier formation and growth factors synthesis, which subsequently inhibited the proliferation and induced the apoptosis of spermatogonia. As for the macrophages, ZnO NPs activated oxidative stress of Raw264.7 cells through nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) pathway and promoted cell apoptosis through extracellular signal-regulated kinase (ERK) 1/2 pathway. Collectively, our work reveals the cell type-specific and cellularly heterogenetic mechanism of ZnO NPs-induced testis damage and paves the path for identifying putative biomarkers and therapeutics against this disorder.

Identifying potential biomarkers for non-obstructive azoospermia using WGCNA and machine learning algorithms

Objective

The cause and mechanism of non-obstructive azoospermia (NOA) is complicated; therefore, an effective therapy strategy is yet to be developed. This study aimed to analyse the pathogenesis of NOA at the molecular biological level and to identify the core regulatory genes, which could be utilised as potential biomarkers.

Methods

Three NOA microarray datasets (GSE45885, GSE108886, and GSE145467) were collected from the GEO database and merged into training sets; a further dataset (GSE45887) was then defined as the validation set. Differential gene analysis, consensus cluster analysis, and WGCNA were used to identify preliminary signature genes; then, enrichment analysis was applied to these previously screened signature genes. Next, 4 machine learning algorithms (RF, SVM, GLM, and XGB) were used to detect potential biomarkers that are most closely associated with NOA. Finally, a diagnostic model was constructed from these potential biomarkers and visualised as a nomogram. The differential expression and predictive reliability of the biomarkers were confirmed using the validation set. Furthermore, the competing endogenous RNA network was constructed to identify the regulatory mechanisms of potential biomarkers; further, the CIBERSORT algorithm was used to calculate immune infiltration status among the samples.

Results

A total of 215 differentially expressed genes (DEGs) were identified between NOA and control groups (27 upregulated and 188 downregulated genes). The WGCNA results identified 1123 genes in the MEblue module as target genes that are highly correlated with NOA positivity. The NOA samples were divided into 2 clusters using consensus clustering; further, 1027 genes in the MEblue module, which were screened by WGCNA, were considered to be target genes that are highly correlated with NOA classification. The 129 overlapping genes were then established as signature genes. The XGB algorithm that had the maximum AUC value (AUC=0.946) and the minimum residual value was used to further screen the signature genes. IL20RB, C9orf117, HILS1, PAOX, and DZIP1 were identified as potential NOA biomarkers. This 5 biomarker model had the highest AUC value, of up to 0.982, compared to other single biomarker models; additionally, the results of this biomarker model were verified in the validation set.

Conclusions

As IL20RB, C9orf117, HILS1, PAOX, and DZIP1 have been determined to possess the strongest association with NOA, these five genes could be used as potential therapeutic targets for NOA patients. Furthermore, the model constructed using these five genes, which possessed the highest diagnostic accuracy, may be an effective biomarker model that warrants further experimental validation.

Single-cell RNA sequencing technology in human spermatogenesis: Progresses and perspectives

Spermatogenesis, a key part of the spermiation process, is regulated by a combination of key cells, such as primordial germ cells, spermatogonial stem cells, and somatic cells, such as Sertoli cells. Abnormal spermatogenesis can lead to azoospermia, testicular tumors, and other diseases related to male infertility. The application of single-cell RNA sequencing (scRNA-seq) technology in male reproduction is gradually increasing with its unique insight into deep mining and analysis. The data cover different periods of neonatal, prepubertal, pubertal, and adult stages. Different types of male infertility diseases including obstructive and non-obstructive azoospermia (NOA), Klinefelter Syndrome (KS), Sertoli Cell Only Syndrome (SCOS), and testicular tumors are also covered. We briefly review the principles and application of scRNA-seq and summarize the research results and application directions in spermatogenesis in different periods and pathological states. Moreover, we discuss the challenges of applying this technology in male reproduction and the prospects of combining it with other technologies.

Identification of a novel pyroptosis-related gene signature in human spermatogenic dysfunction

PURPOSE

To reveal the underlying roles that pyroptosis-related genes (PRGs) played in human spermatogenic dysfunction.

METHODS

One discovery set and three validation sets were employed to inspect the previously reported 33 PRGs in the human testis with different status of spermatogenesis. PRGs that differentially expressed in all sets were considered as key differentially expressed pyroptosis-related genes (PR-DEGs). The relationships between key PR-DEGs and samples' clinicopathological, therapeutic, and immune patterns were respectively studied. Single-cell RNA sequencing (scRNS-seq) analyses were conducted to show the expression changes and related mechanisms of key PR-DEGs at a single-cell resolution.

RESULTS

CASP4 and GPX4 were identified as two key PR-DEGs. These two genes were significantly dysregulated in spermatogenic dysfunctional samples, but with opposite tendency. CASP4 was negatively correlated with Johnsen scores but positively correlated with follicle-stimulating hormone (FSH) levels (all p < 0.05), while GPX4 exhibited significant positive correlations with Johnsen scores and negative relevance with FSH. For treatments, both molecules showed a prospective value of being predictors for sperm retrieval surgeries. Moreover, CASP4 and GPX4 were potential immunoregulators in the testicular immune microenvironment and showed significant correlations to testicular macrophages and mast cell infiltration. In scRNA-seq analyses, GPX4 was highly expressed in germ cells, which therefore suffered a sharp reduction with the loss of germ cells in spermatogenic dysfunction. On the other hand, CASP4 were basically somatic cell-derived, and the proportion of CASP4-positive Leydig cells significantly increased in disease testes (p = 0.0001).

CONCLUSION

In all, we revealed two key PRGs of human testes that might be functional in spermatogenic dysfunction.

Macrophage-Related Testicular Inflammation in Individuals with Idiopathic Non-Obstructive Azoospermia: A Single-Cell Analysis

Male infertility is a global issue that seriously affects reproductive health. This study aimed to understand the underlying causes of idiopathic non-obstructive azoospermia (iNOA), which is a type of male infertility with unknown origins that accounts for 10-15% of cases. By using single-cell analysis techniques, we aimed to uncover the mechanisms of iNOA and gain insight into the cellular and molecular changes in the testicular environment. In this study, we performed bioinformatics analysis using scRNA-seq and microarray data obtained from the GEO database. The analysis included techniques such as pseudotime analysis, cell-cell communication, and hdWGCNA. Our study showed a significant difference between the iNOA and the normal groups, indicating a disorder in the spermatogenic microenvironment in iNOA. We observed a reduction in the proportion of Sertoli cells and blocked germ cell differentiation. Additionally, we found evidence of testicular inflammation related to macrophages and identified ODF2 and CABYR as potential biomarkers for iNOA.

An artificial neural network model to diagnose non-obstructive azoospermia based on RNA-binding protein-related genes

Non-obstructive azoospermia (NOA) is a severe form of male infertility, but its pathological mechanisms and diagnostic biomarkers remain obscure. Since the dysregulation of RNA-binding proteins (RBPs) had nonnegligible effects on spermatogenesis, we aimed to investigate the functions and diagnosis values of RBPs in NOA. 58 testicular samples (control = 11, NOA = 47) from Gene Expression Omnibus (GEO) were set as the training cohort. Three public datasets, containing GSE45885 (control = 4, NOA = 27), GSE45887 (control = 4, NOA = 16), and GSE145467 (control = 10, NOA = 10), and 44 clinical samples from the local hospital (control = 27, NOA = 17) were used for validation. Through a series of bioinformatical analyses and machine learning algorithms, including genomic difference detection, protein-protein interaction network analysis, LASSO, SVM-RFE, and Boruta, DDX20 and NCBP2 were determined as significant predictors of NOA. Single-cell RNA sequencing of 432 testicular cell samples from NOA patients indicated that DDX20 and NCBP2 were associated with spermatogenesis (false discovery rate < 0.05). Based on the transcriptome expressions of DDX20 and NCBP2, we constructed multiple diagnosis models using logistic regression, random forest, and artificial neural network (ANN). The ANN model exhibited the most reliable predictive performance in the training cohort (AUC = 0.840), GSE45885 (AUC = 0.731), GSE45887 (AUC = 0.781), GSE145467 (AUC = 0.850), and local cohort (AUC = 0.623). Totally, an ANN diagnosis model based on RBP DDX20 and NCBP2 was developed and externally validated in NOA, functioning as a promising tool in clinical practice.

Integrative bioinformatics analysis to identify novel biomarkers associated with non-obstructive azoospermia

Aim

This study aimed to identify autophagy-related genes (ARGs) associated with non-obstructive azoospermia and explore the underlying molecular mechanisms.

Methods

Two datasets associated with azoospermia were downloaded from the Gene Expression Omnibus database, and ARGs were obtained from the Human Autophagy-dedicated Database. Autophagy-related differentially expressed genes were identified in the azoospermia and control groups. These genes were subjected to Gene Ontology and Kyoto Encyclopedia of Genes and Genomes, protein–protein interaction (PPI) network, and functional similarity analyses. After identifying the hub genes, immune infiltration and hub gene–RNA-binding protein (RBP)–transcription factor (TF)–miRNA–drug interactions were analyzed.

Results

A total 46 differentially expressed ARGs were identified between the azoospermia and control groups. These genes were enriched in autophagy-associated functions and pathways. Eight hub genes were selected from the PPI network. Functional similarity analysis revealed that HSPA5 may play a key role in azoospermia. Immune cell infiltration analysis revealed that activated dendritic cells were significantly decreased in the azoospermia group compared to those in the control groups. Hub genes, especially ATG3, KIAA0652, MAPK1, and EGFR were strongly correlated with immune cell infiltration. Finally, a hub gene–miRNA–TF–RBP–drug network was constructed.

Conclusion

The eight hub genes, including EGFR, HSPA5, ATG3, KIAA0652, and MAPK1, may serve as biomarkers for the diagnosis and treatment of azoospermia. The study findings suggest potential targets and mechanisms for the occurrence and development of this disease.

Human spermatogonial stem cells and their niche in male (in)fertility: novel concepts from single-cell RNA-sequencing

The amount of single-cell RNA-sequencing (scRNA-seq) data produced in the field of human male reproduction has steadily increased. Transcriptional profiles of thousands of testicular cells have been generated covering the human neonatal, prepubertal, pubertal and adult period as well as different types of male infertility; the latter include non-obstructive azoospermia, cryptozoospermia, Klinefelter syndrome and azoospermia factor deletions. In this review, we provide an overview of transcriptional changes in different testicular subpopulations during postnatal development and in cases of male infertility. Moreover, we review novel concepts regarding the existence of spermatogonial and somatic cell subtypes as well as their crosstalk and provide corresponding marker genes to facilitate their identification. We discuss the potential clinical implications of scRNA-seq findings, the need for spatial information and the necessity to corroborate findings by exploring other levels of regulation, including at the epigenetic or protein level.

Treatment progress of cryptozoospermia with Western Medicine and traditional Chinese medicine: A literature review

Background and Aims

Cryptozoospermia is an extreme oligozoospermia with an unsatisfactory treatment effect, with an incidence rate of approximately 8.73% in male infertility, whose effective solution has become the call of the times. Western Medicine has achieved certain effects through drugs, surgery, and assisted reproductive therapy, but this is still not ideal. Traditional Chinese medicine (TCM) has made many achievements in other disciplines; however, there is still a lack of evidence-based medical evidence to improve sperm production.

Methods

The relevant literatures from the China National Knowledge Internet (CNKI) and PubMed in the past 10 years were collected in this article, of which the mechanisms, advantages, or current controversies of various treatment methods of Western Medicine and TCM were analyzed, to find new treatment methods and research directions.

Results

With the development of modern science and technology, medical treatments for cryptozoospermia have become increasingly abundant; however, there is still no universally recognized unified and effective guiding plan. Although TCM has not been fully verified by evidence-based medicine, most TCM combined with Western Medicine can achieve unexpected results.

Conclusion

The combination of TCM and Western Medicine may become a bane for cryptozoospermia and bring good news to infertile men worldwide.

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.

Single-Cell Transcriptomics-Based Study of Transcriptional Regulatory Features in the Non-Obstructive Azoospermia Testis

Non-obstructive azoospermia (NOA) is one of the most important causes of male infertility. Although many congenital factors have been identified, the aetiology in the majority of idiopathic NOA (iNOA) cases remains unknown. Herein, using single-cell RNA-Seq data sets (GSE149512) from the Gene Expression Omnibus (GEO) database, we constructed transcriptional regulatory networks (TRNs) to explain the mutual regulatory relationship and the causal relationship between transcription factors (TFs). We defined 10 testicular cell types by their marker genes and found that the proportion of Leydig cells (LCs) and macrophages (tMΦ) was significantly increased in iNOA testis. We identified specific TFs including LHX9, KLF8, KLF4, ARID5B and RXRG in iNOA LCs. In addition, we found specific TFs in iNOA tMΦ such as POU2F2, SPIB IRF5, CEBPA, ELK4 and KLF6. All these identified TFs are strongly engaged in cellular fate, function and homeostasis of the microenvironment. Changes in the activity of the above-mentioned TFs might affect the function of LCs and tMΦ and ultimately cause spermatogenesis failure. This study illustrate that these TFs play important regulatory roles in the occurrence and development of NOA.