Microenvironmental signals govern the cellular identity of testicular macrophages

Chronic exposure to polystyrene microplastics induced LHR reduction and decreased testosterone levels through NF-κB pathway

The extensive utilization of plastic products in recent years has resulted in a significant contamination of microplastics (MPs). The ingestion of MPs by aquatic and terrestrial organisms facilitates their transmission to mammals through the food chain. Therefore, the toxicity of MPs has attracted widespread attention from researchers. Previous studies have shown a connection between being exposed to polystyrene MPs (PS-MPs) and issues with male reproductive function. Testosterone, a hormone essential for male reproductive function, is produced and secreted by specialized cells known as Leydig cells, which found in the testicular interstitium. In our prior research, we confirmed that exposure to PS-MPs caused a reduction in testosterone levels by interfering with the LH-mediated LHR/cAMP/PKA/StAR pathway, with LHR being pivotal in this mechanism. However, the molecular mechanism underlying PS-MPs-induced reduction of LHR remains unclear. In this study, mice were respectively given drinking water containing 1000 μg/L PS-MPs characterized by diameters of 0.5 μm, 4 μm, and 10 μm for a period of 180 days. Our findings indicated that exposure to PS-MPs resulted in the proliferation of macrophages as well as their polarization towards the M1 phenotype. Additionally, the presence of PS-MPs triggered the release of tumor necrosis factor alpha (TNF-α) from macrophages, thereby activating nuclear factor-κB (NF-κB) signaling pathway within Leydig cells. The translocation of NF-κB into nucleus facilitated its binding to the promoter region of LHR, which consequently led to the repression of LHR transcription. This transcriptional inhibition resulted in a subsequent suppression of testosterone synthesis and secretion. Overall, this study elucidates a theoretical basis for explaining the interference of PS-MPs on the testosterone synthesis and secretion in Leydig cells from the perspective of the interaction between cells in the testicular interstitium.

Determination of M1/M2 Macrophage Polarization in Ipsilateral and Contralateral Rat Testis Tissue Following Unilateral Torsion/Detorsion

The present study investigates the changes in M1/M2 macrophage polarization resulting from unilateral testicular torsion in the bilateral testis. The study sample included 63 male Sprague-Dawley rats, which were randomly divided into nine groups (n = 7): Control, Sham (4 h (4 h), 24 h, 7 days (7d), 14d), and Torsion/Detorsion (T/D) (4 h, 24 h, 7d, 14d). Histopathological evaluations revealed no changes in the Sham groups, while T/D was noted to cause edema, vascular occlusion, disruption of seminiferous tubule epithelial organization, germ cell abnormalities and structural anomalies in the experimental rats, the severity and extent of which increased from 4 h to 14d after T/D. The Cosentino scores used to determine the degree of histological damage were consistent with the histopathological findings in all groups, while the Johnsen scores, as a marker of spermatogenesis, were lower in the T/D groups. Seminiferous tubule diameters and germinal epithelial thickness decreased significantly in parallel with increased tubule damage in the ipsilateral testicles. Testicular torsion significantly affected sperm motility, with significant reductions observed in the T/D 7d and T/D 14d groups. A hormone profile analysis revealed decreased testosterone levels in both the Sham and T/D groups when compared to the Controls. CD68 and CD163 immunoreactivities, as M1 and M2 macrophage surface markers, were determined in the testicular tissue using the avidin-biotin-peroxidase complex method. T/D interventions caused M1/M2 macrophage polarization changes and increased M1 macrophages, particularly in contralateral testicular tissue. The increase in M1 macrophages in contralateral testicular tissue following T/D in the present study suggests that cell processes, including macrophages, may play an important role in contralateral testicular injury.

Role of macrophage colony stimulating factor and interferon regulatory factor 7 in modulating the immune profile of mouse testicular macrophages

Testicular macrophages (TM) are critical for the function of the testis by regulating homeostasis and inflammatory responses. However, the mechanisms by which TM fulfil these roles remain elusive. In this study, we explored the impact of two key testicular microenvironmental factors, namely 25-hydroxycholesterol (25HC), an oxysterol related to sex hormones and macrophage colony-stimulating factor (M-CSF), a factor crucial for macrophage survival and differentiation, on the regulation of the TM phenotype. Specifically, we examined their role in controlling the expression of the transcription factor interferon regulatory factor 7 (Irf7), a factor critical for maintaining the alternative macrophage phenotype. To achieve this, we used an in vitro bone marrow-derived macrophage (BMDM) model as a surrogate for TM to investigate the roles of 25HC and M-CSF in regulating the expression of Irf7 during the polarization of murine TM. M-CSF was identified as the main regulator of Irf7 expression, while 25HC production is a consequence of Irf7 activation in BMDM. In turn, 25HC plays a role in a negative feedback loop on the expression levels of Irf7 in BMDM. Using flow cytometry in Irf7-/- mouse testis the CD64loMHChi TM subpopulation was found to be decreased. Together with lower IL-10 protein levels in Irf7-/- TM this indicates a shift towards an M1-like macrophage profile. In summary, our data indicates that M-CSF could act as an inducer of high Irf7 expression levels in the mouse testis. However, the exact role of the high 25HC concentration in the testis in maintaining the local immune milieu still needs further study.

An enzyme-free method for isolating testicular macrophages from rodent models

Macrophages are the major type of immune cell in the testis of both humans and rodents. Testicular macrophages (TMs) play critical roles in maintaining the testicular microenvironment, such as Leydig cell-dependent hormone production, spermatogenesis, and immune balance. A substantial number of studies have used rodent models to investigate the functions of TMs with various methods and harvest macrophages from the testis. Studies have demonstrated that enzyme digestion, an essential part of these methods, can improve the number and purity of TMs while unavoidably altering the immunoprofile of macrophages, which is detrimental for further study in terms of immune investigation. Here, we modified the existing method of microglia isolation and set up a novel method without the enzyme digestion step to isolate TMs. According to the characteristics of testicular tissue looseness and the physical and biological characteristics of macrophages, by combining mechanical separation, gradient centrifugation, and immuno-magnetic bead selection, we can effectively avoid the enzymatic digestion of testis tissue and maintain the immune characteristics of macrophages. Additionally, we verified the purity of TM with flow cytometry (FC) at approximately 91-95%, and the production of tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) was lower than that isolated with enzyme digestion. In contrast to the traditional method, this novel protocol can assist those who have no convenient access to fluorescence-activated cell sorting (FACS) to isolate a sufficient number of TMs and, most importantly, avoid altering the immunoprofile of TMs without enzyme digestion.

AEC and AFMSC Transplantation Preserves Fertility of Experimentally Induced Rat Varicocele by Expressing Differential Regenerative Mechanisms

Amniotic membrane and amniotic fluid derived cells are regarded as a promising stem cell source for developing regenerative medicine techniques, although they have never been tested on male infertility diseases such as varicocele (VAR). The current study aimed to examine the effects of two distinct cell sources, human Amniotic Fluid Mesenchymal Stromal Cells (hAFMSCs) and amniotic epithelial cells (hAECs), on male fertility outcomes in a rat induced VAR model. To explain cell-dependent enhancement of reproductive outcomes in rats transplanted with hAECs and hAFMSCs, insights on testis morphology, endocannabinoid system (ECS) expression and inflammatory tissue response have been carried out alongside cell homing assessment. Both cell types survived 120 days post-transplantation by modulating the ECS main components, promoting proregenerative M2 macrophages (Mφ) recruitment and a favorable anti-inflammatory IL10 expression pattern. Of note, hAECs resulted to be more effective in restoring rat fertility rate by enhancing both structural and immunoresponse mechanisms. Moreover, immunofluorescence analysis revealed that hAECs contributed to CYP11A1 expression after transplantation, whereas hAFMSCs moved towards the expression of Sertoli cell marker, SOX9, confirming a different contribution into the mechanisms leading to testis homeostasis. These findings highlight, for the first time, a distinct role of amniotic membrane and amniotic fluid derived cells in male reproduction, thus proposing innovative targeted stem-based regenerative medicine protocols for remedying high-prevalence male infertility conditions such as VAR.

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.

Immune checkpoint inhibitors and Chimeric Antigen Receptor (CAR)-T cell therapy: Potential treatment options against Testicular Germ Cell Tumors

Germ cell tumors (GCTs) represent a heterogeneous neoplasm family affecting gonads and rarely occurring in extragonadal areas. Most of patients have a good prognosis, often even in the presence of metastatic disease; however, in almost 15% of cases, tumor relapse and platinum resistance are the main challenges. Thus, novel treatment strategies with both improved antineoplastic activity and minor treatment-related adverse events compared with platinum are really expected. In this context, the development and the high activity demonstrated by immune checkpoint inhibitors in solid tumors and, subsequently, the interesting results obtained from the use of chimeric antigen receptor (CAR-) T cell therapy in hematological tumors, have stimulated research in this direction also in GCTs. In this article, we will analyze the molecular mechanisms underlying the immune action in the development of GCTs, and we will report the data from the studies that tested the new immunotherapeutic approaches in these neoplasms.

Testicular Immunity and Its Connection with the Microbiota. Physiological and Clinical Implications in the Light of Personalized Medicine

Reproduction is a complex process, which is based on the cooperation between the endocrine-immune system and the microbiota. Testicular immunity is characterized by the so-called immune privilege, a mechanism that avoids autoimmune attacks against proteins expressed by spermatozoa. Testicular microbiota is connected with the gut microbiota, the most prevalent site of commensals inthe body. Both microbiotas take part inthe development of the immune system and protection againstpathogen invasion. Dysbiosis is caused by concurrent pathologies, such as obesity, diabetes, infections and trauma. The substitution of beneficial bacteria with pathogens may lead to destruction of spermatozoa directly or indirectly and, ultimately, to male infertility. Novel therapeutic interventions, i.e., nutritional interventions and supplementation of natural products, such as, probiotics, prebiotics, antioxidants and polyphenols, may lead to the restoration of the otherwise-impaired male reproductive potential, even if experimental and clinical results are not always concordant. In this review, the structure and immune function of the testis will be described with special reference to the blood-testisbarrier. The regulatory role of both the gut and testicular microbiota will be illustrated in health and disease, also emphasizing therapeutic attempts with natural products for the correction of male infertility, in the era of personalized medicine.

Profiling the 3D interaction between germ cell tumors and microenvironmental cells at the transcriptome and secretome level

The tumor microenvironment (TM), consisting of the extracellular matrix (ECM), fibroblasts, endothelial cells and immune cells, might affect tumor invasiveness and the outcome of standard chemotherapy. This study investigated the cross-talk between germ cell tumors (GCT) and surrounding TM cells (macrophages, T-lymphocytes, endothelial cells, fibroblasts) at the transcriptome and secretome level. Using high-throughput approaches of three-dimensional (3D) co-cultured cellular aggregates, this study offers newly identified pathways to be studied with regard to sensitivity towards cisplatin-based chemotherapy or tumor invasiveness as a consequence of the cross-talk between tumor cells and TM components. Mass-spectrometry-based secretome analyses revealed that TM cells secreted factors involved in ECM organization, cell adhesion, angiogenesis and regulation of insulin-like growth factor (IGF) transport. To evaluate direct cell-cell contacts, green fluorescent protein (GFP)-expressing GCT cells and mCherry-expressing TM cells were co-cultured in 3D. Afterwards, cell populations were separated by flow cytometry and analyzed by RNA-sequencing. Correlating the secretome with transcriptome data indicated molecular processes such as cell adhesion and components of the ECM being enriched in most cell populations. Re-analyses of secretome data with regard to lysine- and proline-hydroxylated peptides revealed a gain in proteins, such as collagens and fibronectin. Cultivation of GCT cells on collagen I/IV- or fibronectin-coated plates significantly elevated adhesive and migratory capacity, while decreasing cisplatin sensitivity of GCT cells. Correspondingly, cisplatin sensitivity was significantly reduced in GCT cells under the influence of conditioned medium from fibroblasts and endothelial cells. This study sheds light on the cross-talk between GCT cells and their circumjacent TM, which results in deposition of the ECM and eventually promotes a pro-tumorigenic environment through enhanced migratory and adhesive capacity, as well as decreased cisplatin sensitivity. Hence, our observations indicate that targeting the ECM and its cellular components might be a novel therapeutic option in combination with cisplatin-based chemotherapy for GCT patients.

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.

Eicosanoid Biosynthesis in Male Reproductive Development: Effects of Perinatal Exposure to NSAIDs and Analgesic Drugs

Increasing rates of infertility associated with declining sperm counts and quality, as well as increasing rates of testicular cancer are contemporary issues in the United States and abroad. These conditions are part of the Testicular Dysgenesis Syndrome, which includes a variety of male reproductive disorders hypothesized to share a common origin based on disrupted testicular development during fetal and neonatal stages of life. Male reproductive development is a highly regulated and complex process that relies on an intricate coordination between germ, Leydig, and Sertoli cells as well as other supporting cell types, to ensure proper spermatogenesis, testicular immune privilege, and endocrine function. The eicosanoid system has been reported to be involved in the regulation of fetal and neonatal germ cell development as well as overall testicular homeostasis. Moreover, non-steroidal anti-inflammatory drugs (NSAIDs) and analgesics with abilities to block eicosanoid synthesis by targeting either or both isoforms of cyclooxygenase enzymes, have been found to adversely affect male reproductive development. This review will explore the current body of knowledge on the involvement of the eicosanoid system in male reproductive development, as well as discuss adverse effects of NSAIDs and analgesic drugs administered perinatally, focusing on toxicities reported in the testis and on major testicular cell types. Rodent and epidemiological studies will be corroborated by findings in invertebrate models for a comprehensive report of the state of the field, and to add to our understanding of the potential long-term effects of NSAID and analgesic drug administration in infants.

Characterization of testicular macrophagesubpopulations in mice

Testis is an immune privileged site, a feature that prevents germ cells from eliciting an autoimmune response. Macrophages contribute to this state of tolerance by adopting an immunoregulatory phenotype. Here, we further characterized their features in mice by analyzing surface markers, anatomic localization as well as morphology and function. Testicular macrophages (TMF) were stained for various surface receptors, and MHCII and CD206 were found to be most suitable to discriminate between two subpopulations. Our immunohistochemical analysis further confirmed a predominant localization of CD206+ cells in the interstitial space. Imaging flow cytometry revealed that both subtypes of TMF differed in size and contrast, and to some extent also in their ability to engulf high-molecular dextran. To investigate whether the polarization of the immune system had any influence on the phenotype of TMF, we compared C57BL/6 and BALB/c mice. Importantly, our analysis revealed that the abundance of cells expressing either MHCII or any of the scavenger receptors CD206, CD163 and CD71 differed between both mouse strains. In addition, the presence of the glucocorticoid receptor in macrophages affected the ratio between individual subpopulations, which is consistent with a crucial role of glucocorticoids in macrophage polarization. Collectively, our results indicate that TMF are composed in a variable ratio of distinct subsets with characteristic features, which may shape the immune privilege of the testis also in humans.

Testicular macrophages: development and function in health and disease

Macrophages comprise a heterogeneous immune cell population and display niche-specific phenotypes and functions in almost all organs. Testicular macrophages (TMs) perform essential immune and non-immune functions in the mammalian male gonads. Here, we discuss the most recent findings on TM ontogeny, heterogeneity, and function under steady state and inflammatory conditions. We also highlight new discoveries regarding the functions of macrophages during bacterial and viral infections of the testes and how macrophages may indirectly help the establishment of a reservoir through virus seeding. Understanding TM function and macrophage-related mechanisms of disease might assist in developing new opportunities for intervention in male infertility.

Testosterone in COVID-19: An Adversary Bane or Comrade Boon

COVID-19 is a pandemic disease caused by severe acute respiratory coronavirus 2 (SARS-CoV-2), which leads to pulmonary manifestations like acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). In addition, COVID-19 may cause extra-pulmonary manifestation such as testicular injury. Both high and low levels of testosterone could affect the severity of COVID-19. Herein, there is substantial controversy regarding the potential role of testosterone in SARS-CoV-2 infection and COVID-19 severity. Therefore, the present study aimed to review and elucidate the assorted view of preponderance regarding the beneficial and harmful effects of testosterone in COVID-19. A related literature search in PubMed, Scopus, Web of Science, Google Scholar, and Science Direct was done. All published articles related to the role of testosterone and COVID-19 were included in this mini-review. The beneficial effects of testosterone in COVID-19 are through inhibition of pro-inflammatory cytokines, augmentation of anti-inflammatory cytokines, modulation of the immune response, attenuation of oxidative stress, and endothelial dysfunction. However, its harmful effects in COVID-19 are due to augmentation of transmembrane protease serine 2 (TMPRSS2), which is essential for cleaving and activating SARS-CoV-2 spike protein during acute SARS-CoV-2 infection. Most published studies illustrated that low testosterone levels are linked to COVID-19 severity. A low testosterone level in COVID-19 is mainly due to testicular injury, the primary source of testosterone.

Somatic-Immune Cells Crosstalk In-The-Making of Testicular Immune Privilege

Immunological infertility contributes significantly to the etiology of idiopathic male infertility. Shielding the spermatogenic cells from systemic immune responses is fundamental to secure normal production of spermatozoa. The body's immune system is tuned with the host self-components since the early postnatal period, while sperm first develops during puberty, thus rendering spermatogenic proteins as 'non-self' or 'antigenic.' Development of antibodies to these antigens elicits autoimmune responses affecting sperm motility, functions, and fertility. Therefore, the testes need to establish a specialized immune-privileged microenvironment to protect the allogenic germ cells by orchestration of various testicular cells and resident immune cells. This is achieved through sequestration of antigenic germ cells by blood-testis barrier and actions of various endocrine, paracrine, immune-suppressive, and immunomodulatory mechanisms. The various mechanisms are very complex and need conceptual integration to disclose the exact physiological scenario, and to facilitate detection and management of immunogenic infertility caused by disruption of testicular immune regulation. The present review aims to (a) discuss the components of testicular immune privilege; (b) explain testicular somatic and immune cell interactions in establishing and maintaining the testicular immune micro-environment; and (c) illustrate the integration of multiple mechanisms involved in the control of immune privilege of the testis.

Impaired macrophages and failure of steroidogenesis and spermatogenesis in rat testes with cytokines deficiency induced by diacerein

The role of cytokines in testicular function under normal conditions has not been completely understood. Here, we evaluated testicular macrophages (TM), steroidogenesis by Leydig cells (LC) and seminiferous tubules integrity in cytokines-deficient rat testes induced by diacerein, an anti-inflammatory drug that inhibits interleukin-1 (IL-1) and tumor necrosis factor-alpha (TNF-α). Male rats received daily 100 mg/kg of diacerein (DIAG; n = 8) or saline (CG; n = 8) for 30 days. Serum testosterone (T) levels were measured and the seminiferous tubule (ST) area, epithelial area (EA), frequency of damaged ST and number of Sertoli cells (SC) were evaluated. TUNEL method and immunoreactions for detection of pro-IL-1β, TNF-α, steroidogenic acute regulatory protein (StAR), 17β-hydroxysteroid dehydrogenase (17β-HSD), androgen receptor (AR) and scavenger receptor for hemoglobin-haptoglobin complexes (CD163), a TM marker, were performed. Testicular AR, 17β-HSD and IL-1β levels were detected by Western blot. Data were submitted to Student t test (p ≤ 0.05). In DIAG, T and testicular AR, 17β-HSD and IL-1β levels decreased significantly (p < 0.05). The number of TUNEL-positive interstitial cells increased and LC showed weak StAR, 17β-HSD and AR immunoexpression in association with reduced IL-1β immunoexpression and number of CD163-positive TM in the interstitial tissue from diacerein-treated rats. Numerous damaged ST were found in DIAG, and reduction in the EA were associated with germ cells death. Moreover, the number of SC reduced and weak AR and TNF-α immunoexpression was observed in SC and germ cells, respectively. The cytokines deficiency induced by diacerein impairs TM, LC and spermatogenesis, and points to a role of IL-1β in steroidogenesis under normal conditions. In the ST, the weak AR and TNF-α immunoexpression in SC and germ cells, respectively, reinforces the idea that TNF-α plays a role in the SC androgenic control.

Sperm proteins and cancer-testis antigens are released by the seminiferous tubules in mice and men

Sperm develop from puberty in the seminiferous tubules, inside the blood-testis barrier to prevent their recognition as "non-self" by the immune system, and it is widely assumed that human sperm-specific proteins cannot access the circulatory or immune systems. Sperm-specific proteins aberrantly expressed in cancer, known as cancer-testis antigens (CTAs), are often pursued as cancer biomarkers and therapeutic targets based on the assumption they are neoantigens absent from the circulation in healthy men. Here, we identify a wide range of germ cell-derived and sperm-specific proteins, including multiple CTAs, that are selectively deposited by the Sertoli cells of the adult mouse and human seminiferous tubules into testicular interstitial fluid (TIF) that is "outside" the blood-testis barrier. From TIF, the proteins can access the circulatory- and immune systems. Disruption of spermatogenesis decreases the abundance of these proteins in mouse TIF, and a sperm-specific CTA is significantly decreased in TIF from infertile men, suggesting that exposure of certain CTAs to the immune system could depend on fertility status. The results provide a rationale for the development of blood-based tests useful in the management of male infertility and indicate CTA candidates for cancer immunotherapy and biomarker development that could show sex-specific and male-fertility-related responses.

Identification of molecular biomarkers associated with disease progression in the testis of bulls infected with Besnoitia besnoiti

Breeding bulls infected with Besnoitia besnoiti may develop sterility during either acute or chronic infection. The aim of this study was to investigate the molecular pathogenesis of B. besnoiti infection with prognosis value in bull sterility. Accordingly, five well-characterized groups of naturally and experimentally infected males were selected for the study based on clinical signs and lesions compatible with B. besnoiti infection, serological results and parasite detection. A broad panel of molecular markers representative of endothelial activation and fibrosis was investigated and complemented with a histopathological approach that included conventional histology and immunohistochemistry. The results indicated the predominance of an intense inflammatory infiltrate composed mainly of resident and recruited circulating macrophages and to a lesser extent of CD3+ cells in infected bulls. In addition, a few biomarkers were associated with acute, chronic or subclinical bovine besnoitiosis. The testicular parenchyma showed a higher number of differentially expressed genes in natural infections (acute and chronic infections) versus scrotal skin in experimental infections (subclinical infection). In subclinical infections, most genes were downregulated except for the CCL24 and CXCL2 genes, which were upregulated. In contrast, the acute phase was mainly characterized by the upregulation of IL-1α, IL-6 and TIMP1, whereas in the chronic phase, the upregulation of ICAM and the downregulation of MMP13, PLAT and IL-1α were the most relevant findings. Macrophages could be responsible for the highest level of gene regulation in the testicular parenchyma of severely affected and sterile bulls, and all these genes could be prognostic markers of sterility.

Impacts of Immunometabolism on Male Reproduction

The physiological process of male reproduction relies on the orchestration of neuroendocrine, immune, and energy metabolism. Spermatogenesis is controlled by the hypothalamic-pituitary-testicular (HPT) axis, which modulates the production of gonadal steroid hormones in the testes. The immune cells and cytokines in testes provide a protective microenvironment for the development and maturation of germ cells. The metabolic cellular responses and processes in testes provide energy production and biosynthetic precursors to regulate germ cell development and control testicular immunity and inflammation. The metabolism of immune cells is crucial for both inflammatory and anti-inflammatory responses, which supposes to affect the spermatogenesis in testes. In this review, the role of immunometabolism in male reproduction will be highlighted. Obesity, metabolic dysfunction, such as type 2 diabetes mellitus, are well documented to impact male fertility; thus, their impacts on the immune cells distributed in testes will also be discussed. Finally, the potential significance of the medicine targeting the specific metabolic intermediates or immune metabolism checkpoints to improve male reproduction will also be reassessed.

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

OBJECTIVE

Immune cells residing in the testicular interstitial space form the immunological microenvironment of the testis. They are assumed to play a role in maintaining testicular homeostasis and immune privilege. However, the immune status and related cell polarization in patients with nonobstructive azoospermia (NOA) remains poorly characterized. System evaluation of the testis immunological microenvironment in NOA patients may help to reveal the mechanisms of idiopathic azoospermia.

STUDY DESIGN

The gene expression patterns of immune cells in normal human testes were systematically analyzed by single-cell RNA sequencing (scRNA-seq) and preliminarily verification by the human protein atlas (HPA) online database. The immune cell infiltration profiles and immune status of patients with NOA was analyzed by single-sample gene set enrichment analysis (ssGSEA) and gene set variation analysis (GSVA) based on four independent public microarray datasets (GSE45885, GSE45887, GSE9210, and GSE145467), obtained from Gene Expression Omnibus (GEO) online database. The relationship between immune cells and spermatogenesis score was further analyzed by Spearman correlation analysis. Finally, immunohistochemistry (IHC) staining was performed to identify the main immune cell types and their polarization status in patients with NOA.

RESULTS

Both scRNA-seq and HPA analysis showed that testicular macrophages represent the largest pool of immune cells in the normal testis, and also exhibit an attenuated inflammatory response by expressing high levels of tolerance proteins (CD163, IL-10, TGF-β, and VEGF) and reduced expression of TLR signaling pathway-related genes. Correlation analysis revealed that the testicular immune score and macrophages including M1 and M2 macrophages were significantly negatively correlated with spermatogenesis score in patients with NOA (GSE45885 and GSE45887). In addition, the number of M1 and M2 macrophages was significantly higher in patients with NOA (GSE9210 and GSE145467) than in normal testis. GSVA analysis indicated that the immunological microenvironment in NOA tissues was manifested by activated immune system and pro-inflammatory status. IHC staining results showed that the number of M1 and M2 macrophages was significantly higher in NOA tissues than in normal testis and negatively correlated with the Johnson score.

CONCLUSION

Testicular macrophage polarization may play a vital role in NOA development and is a promising potential therapeutic target.

Exploring the Ion Channel TRPV2 and Testicular Macrophages in Mouse Testis

The cation channel TRPV2 is known to be expressed by murine macrophages and is crucially involved in their functionality. Macrophages are frequent cells of the mouse testis, an immune-privileged and steroid-producing organ. TRPV2 expression by testicular macrophages and possible changes associated with age or inflammation have not been investigated yet. Therefore, we studied testes of young adult and old wild-type (WT) and AROM⁺ mice, i.e., transgenic mice overexpressing aromatase. In these animals, inflammatory changes are described in the testis, involving active macrophages, which increase with age. This is associated with impaired spermatogenesis and therefore AROM⁺ mice are a model for male infertility associated with sterile inflammation. In WT animals, testicular TRPV2 expression was mapped to interstitial CD206⁺ and peritubular MHC II⁺ macrophages, with higher levels in CD206⁺ cells. Expression levels of TRPV2 and most macrophage markers did not increase significantly in old mice, with the exception of CD206. As the number of TRPV2⁺ testicular macrophages was relatively small, their possible involvement in testicular functions and in aging in WT mice remains to be further studied. In AROM⁺ testis, TRPV2 was readily detected and levels increased significantly with age, together with macrophage markers and TNF-α. TRPV2 co-localized with F4/80 in macrophages and further studies showed that TRPV2 is mainly expressed by unusual CD206⁺MHC II⁺ macrophages, arising in the testis of these animals. Rescue experiments (aromatase inhibitor treatment and crossing with ERαKO mice) restored the testicular phenotype and also abolished the elevated expression of TRPV2, macrophage and inflammation markers. This suggests that TRPV2⁺ macrophages of the testis are part of an inflammatory cascade initiated by an altered sex hormone balance in AROM⁺ mice. The changes in testis are distinct from the described alterations in other organs of AROM⁺, such as prostate and spleen. When we monitored TRPV2 levels in another immune-privileged organ, namely the brain, we found that levels of TRPV2 were not elevated in AROM⁺ and remained stable during aging. In the adrenal, which similar to the testis produces steroids, we found slight, albeit not significant increases in TRPV2 in both AROM⁺ and WT mice, which were associated with age. Thus, the changes in the testis are specific for this organ.

Targeted disruption of galectin 3 in mice delays the first wave of spermatogenesis and increases germ cell apoptosis

Galectin 3 is a multifunctional lectin implicated in cellular proliferation, differentiation, adhesion, and apoptosis. This lectin is broadly expressed in testicular somatic cells and germ cells, and is upregulated during testicular development. Since the role of galectin 3 in testicular function remains elusive, we aimed to characterize the role of galectin 3 in testicular physiology. We found that galectin 3 transgenic mice (Lgals3-/-) exhibited significantly decreased testicular weight in adulthood compared to controls. The transgenic mice also exhibited a delay to the first wave of spermatogenesis, a decrease in the number of germ cells at postnatal day 5 (P5) and P15, and defective Sertoli cell maturation. Mechanistically, we found that Insulin-like-3 (a Leydig cell marker) and enzymes involved in steroid biosynthesis were significantly upregulated in adult Lgals3-/- testes. These observations were accompanied by increased serum testosterone levels. To determine the underlying causes of the testicular atrophy, we monitored cellular apoptosis. Indeed, adult Lgals3-/- testicular cells exhibited an elevated apoptosis rate that is likely driven by downregulated Bcl-2 and upregulated Bax and Bak expression, molecules responsible for live/death cell balance. Moreover, the percentage of testicular macrophages within CD45+ cells was decreased in Lgals3-/- mice. These data suggest that galectin 3 regulates spermatogenesis initiation and Sertoli cell maturation in part, by preventing germ cells from undergoing apoptosis and regulating testosterone biosynthesis. Going forward, understanding the role of galectin 3 in testicular physiology will add important insights into the factors governing the development of germ cells and steroidogenesis and delineate novel biomarkers of testicular function.

Immune and vascular contributions to organogenesis of the testis and ovary

Gonad development is a highly regulated process that coordinates cell specification and morphogenesis to produce sex-specific organ structures that are required for fertility, such as testicular seminiferous tubules and ovarian follicles. While sex determination occurs within specialized gonadal supporting cells, sexual differentiation is evident throughout the entire organ, including within the interstitial compartment, which contains immune cells and vasculature. While immune and vascular cells have been traditionally appreciated for their supporting roles during tissue growth and homeostasis, an increasing body of evidence supports the idea that these cell types are critical drivers of sexually dimorphic morphogenesis of the gonad. Myeloid immune cells, such as macrophages, are essential for multiple aspects of gonadogenesis and fertility, including for forming and maintaining gonadal vasculature in both sexes at varying stages of life. While vasculature is long known for supporting organ growth and serving as an export mechanism for gonadal sex steroids in utero, it is also an important component of fetal testicular morphogenesis and differentiation; additionally, it is vital for ovarian corpus luteal function and maintenance of pregnancy. These findings point toward a new paradigm in which immune cells and blood vessels are integral components of sexual differentiation and organogenesis. In this review, we discuss the state of the field regarding the diverse roles of immune and vascular cells during organogenesis of the testis and ovary and highlight outstanding questions in the field that could stimulate new research into these previously underappreciated constituents of the gonad.

Characterization of DDX4 Gene Expression in Human Cases with Non-Obstructive Azoospermia and in Sterile and Fertile Mice

Background

In mammals, spermatogenesis is the main process for male fertility that is initiated by spermatogonial stem cells (SSCs) proliferation. SSCs are unipotent progenitor cells accountable for transferring the genetic information to the following generation by differentiating to haploid cells during spermato-and spermiogenesis. DEAD-box helicase 4 (DDX4) is a specific germ cell marker and its expression pattern is localized to, spermatocytes, and spermatids. The expression in the SSCs on the basement membrane of the seminiferous tubules is low.

Methods

Immunohistochemistry (IHC) and Fluidigm reverse transcriptase-polymerase chain reaction (RT-PCR) were used to analyze the expression of DDX4 in testis tissue of fertile and sterile mice and human cases with non-obstructive azoospermia.

Results

Our immunohistochemical findings of fertile and busulfan-treated mice showed expression of DDX4 in the basal and luminal compartment of seminiferous tubules of fertile mice whereas no expression was detected in busulfan-treated mice. The immunohistochemical analysis of two human cases with different levels of non-obstructive azoospermia revealed more luminal DDX4 positive cells.

Conclusion

Our findings indicate that DDX4 might be a valuable germ cell marker for analyzing the pathology of germ cell tumors and infertility as global urological problems.

Macrophage ubiquitin-specific protease 2 contributes to motility, hyperactivation, capacitation, and in vitro fertilization activity of mouse sperm

Macrophages are innate immune cells that contribute to classical immune functions and tissue homeostasis. Ubiquitin-specific protease 2 (USP2) controls cytokine production in macrophages, but its organ-specific roles are still unknown. In this study, we generated myeloid-selective Usp2 knockout (msUsp2KO) mice and specifically explored the roles of testicular macrophage-derived USP2 in reproduction. The msUsp2KO mice exhibited normal macrophage characteristics in various tissues. In the testis, macrophage Usp2 deficiency negligibly affected testicular macrophage subpopulations, spermatogenesis, and testicular organogenesis. However, frozen-thawed sperm derived from msUsp2KO mice exhibited reduced motility, capacitation, and hyperactivation. In addition, macrophage Usp2 ablation led to a decrease in the sperm population exhibiting high intracellular pH, calcium influx, and mitochondrial membrane potential. Interrupted pronuclei formation in eggs was observed when using frozen-thawed sperm from msUsp2KO mice for in vitro fertilization. Administration of granulocyte macrophage-colony stimulating factor (GM-CSF), whose expression was decreased in testicular macrophages derived from msUsp2KO mice, restored mitochondrial membrane potential and total sperm motility. Our observations demonstrate a distinct role of the deubiquitinating enzyme in organ-specific macrophages that directly affect sperm function.

Gland Macrophages: Reciprocal Control and Function within Their Niche

The human body contains dozens of endocrine and exocrine glands, which regulate physiological processes by secreting hormones and other factors. Glands can be subdivided into contiguous tissue modules, each consisting of an interdependent network of cells that together perform particular tissue functions. Among those cells are macrophages, a diverse type of immune cells endowed with trophic functions. In this review, we discuss recent findings on how resident macrophages support tissue modules within glands via the creation of mutually beneficial cell-cell circuits. A better comprehension of gland macrophage function and local control within their niche is essential to achieve a refined understanding of gland physiology in homeostasis and disease.

Corticosterone Enhances the AMPK-Mediated Immunosuppressive Phenotype of Testicular Macrophages During Uropathogenic Escherichia coli Induced Orchitis

Testicular macrophages (TM) play a central role in maintaining testicular immune privilege and protecting spermatogenesis. Recent studies showed that their immunosuppressive properties are maintained by corticosterone in the testicular interstitial fluid, but the underlying molecular mechanisms are unknown. In this study, we treated mouse bone marrow-derived macrophages (BMDM) with corticosterone (50 ng/ml) and uncovered AMP-activated protein kinase (AMPK) activation as a critical event in M2 polarization at the phenotypic, metabolic, and cytokine production level. Primary TM exhibited remarkably similar metabolic and phenotypic features to corticosterone-treated BMDM, which were partially reversed by AMPK-inhibition. In a murine model of uropathogenic E. coli-elicited orchitis, intraperitoneal injection with corticosterone (0.1mg/day) increased the percentage of M2 TM in vivo, in a partially AMPK-dependent manner. This study integrates the influence of corticosterone on M2 macrophage metabolic pathways, phenotype, and function, and highlights a promising new avenue for the development of innovative therapeutics for orchitis patients.

Testicular immune cell populations and macrophage polarisation in adult male mice and the influence of altered activin A levels

Detailed morphological characterization of testicular leukocytes in the adult CX₃CR₁^gfp/+ transgenic mouse identified two distinct CX₃CR₁⁺ mononuclear phagocyte (macrophage and dendritic cell) populations: stellate/dendriform cells opposed to the seminiferous tubules (peritubular), and polygonal cells associated with Leydig cells (interstitial). Using confocal microscopy combined with stereological enumeration of CX₃CR₁^gfp/+ cells established that there were twice as many interstitial cells (68%) as peritubular cells (32%). Flow cytometric analyses of interstitial cells from mechanically-dissociated testes identified multiple mononuclear phagocyte subsets based on surface marker expression (CX₃CR₁, F4/80, CD11c). These cells comprised 80% of total intratesticular leukocytes, as identified by CD45 expression. The remaining leukocytes were CD3⁺ (T lymphocytes) and NK1.1⁺ (natural killer cells). Functional phenotype assessment using CD206 (an anti-inflammatory/M2 marker) and MHC class II (an activation marker) identified a potentially tolerogenic CD206⁺MHCII⁺ sub-population (12% of total CD45⁺ cells). Rare testicular subsets of CX₃CR₁⁺CD11c⁺F4/80⁺ (4.3%) mononuclear phagocytes and CD3⁺NK1.1⁺ (3.1%) lymphocytes were also identified for the first time. In order to examine the potential for the immunoregulatory cytokine, activin A to modulate testicular immune cell populations, testes from adult mice with reduced activin A (Inhba^+/-) or elevated activin A (Inha^+/-) were assessed using flow cytometry. Although the proportion of F4/80⁺CD11b⁺ leukocytes (macrophages) was not affected, the frequency of CD206⁺MHCII⁺cells was significantly lower and CD206⁺MHCII^- correspondingly higher in Inha^+/- testes. This shift in expression of MHCII in CD206⁺ macrophages indicates that changes in circulating and/or local activin A influence resident macrophage activation and phenotype and, therefore, the immunological environment of the testis.

Zika virus tropism during early infection of the testicular interstitium and its role in viral pathogenesis in the testes

Sexual transmission and persistence of Zika virus (ZIKV) in the testes pose new challenges for controlling virus outbreaks and developing live-attenuated vaccines. It has been shown that testicular infection of ZIKV is initiated in the testicular interstitium, followed by spread of the virus in the seminiferous tubules. This leads to testicular damage and/or viral dissemination into the epididymis and eventually into semen. However, it remains unknown which cell types are targeted by ZIKV in the testicular interstitium, and what is the specific order of infectious events leading to ZIKV invasion of the seminiferous tubules. Here, we demonstrate that interstitial leukocytes expressing mir-511-3p microRNA are the initial targets of ZIKV in the testes, and infection of mir-511-3p-expressing cells in the testicular interstitium is necessary for downstream infection of the seminiferous tubules. Mir-511-3p is expressed concurrently with CD206, a marker of lineage 2 (M2) macrophages and monocyte derived dendritic cells (moDCs). Selective restriction of ZIKV infection of CD206-expressing M2 macrophages/moDCs results in the attenuation of macrophage-associated inflammatory responses in vivo and prevents the disruption of the Sertoli cell barrier in vitro. Finally, we show that targeting of viral genome for mir-511-3p significantly attenuates early ZIKV replication not only in the testes, but also in many peripheral organs, including spleen, epididymis, and pancreas. This incriminates M2 macrophages/moDCs as important targets for visceral ZIKV replication following hematogenous dissemination of the virus from the site of infection.

Long-term effects of acute cadmium exposure on testis immune privilege

Cadmium (Cd) is a widespread and non-biodegradable pollutant of great concern to human health. This element can affect cellular signal transduction and cell-to-cell interaction in the testis. Immune tolerance towards auto- and alloantigens is an important component of testis immunity. It is involved in spermatogenesis and hormone secretion. Plus, the immune tolerance may help to reveal the changes in testis immunity over a long period after Cd exposure. The current research was aimed at investigating the long-term effects of acute Cd exposure on testis immunity by means of elicitation of testicular immune cell composition shift induced by Cd. Cadmium chloride was intraperitoneally injected at 3 mg Cd/kg to mice. After that testis interstitial cells were stained with surface markers for leukocyte and lymphocyte subpopulations (CD45, CD11b, CD3, CD4, CD8, CD25) and analyzed cytofluorimetrically by week 4, 6, 8 and 12 after Cd administration (Cd group). To identify the delayed effects of cadmium on immune tolerance two groups of animals were subjected to intratesticular allotransplantation of neonatal testis (groups ITT and Cd+ ITT). One of the groups was administered with Cd four weeks before the transplantation (Cd+ITT group). I group served as a control that did not undergo any transplantation or Cd injection. For a better demonstration of the phenomenon of immunological tolerance of the testicles, an additional group (UKT group) was used which got grafts under the kidney capsule (non-immune privileged site).Investigation of the cell population showed that CD45+, CD11b+, CD4+, CD8+ cells were permanently present in testicular interstitial tissue in I group. Intratesticular testis transplantation increased the proportion of CD11b+ but did not have such a pronounced effect on CD8+ cells in ITT group. Moreover, the transplantation elevated CD4+ CD25+ cells known for their immunosuppressive property and promoted graft development by week 2 (histological data). Cd injection resulted in severe inflammation that quenched by week 4 (Cd and Cd+ ITT groups). This time point was chosen for transplantation in Cd+ ITT group. Such Cd pretreatment led to a high CD8+ cell proportion and to the delayed appearance of CD4+ CD25+ cells by week 2 (Cd+ ITTgroup). The finding is consistent with the impairment of graft development in Cd+ ITTgroup pretreated with Cd. Observation suggest that Cd pretreatment was associated with disproportion of interstitial immune cell populations which resulted in the impairment of immunoprotective function of the testis. The impairment of testis immunity showed itself only after several weeks of Cd administration, and only when the recipient testis immunity was provoked by alloantigens of donor testes.

From Ancient to Emerging Infections: The Odyssey of Viruses in the Male Genital Tract

The male genital tract (MGT) is the target of a number of viral infections that can have deleterious consequences at the individual, offspring, and population levels. These consequences include infertility, cancers of male organs, transmission to the embryo/fetal development abnormalities, and sexual dissemination of major viral pathogens such as human immunodeficiency virus (HIV) and hepatitis B virus. Lately, two emerging viruses, Zika and Ebola, have additionally revealed that the human MGT can constitute a reservoir for viruses cleared from peripheral circulation by the immune system, leading to their sexual transmission by cured men. This represents a concern for future epidemics and further underlines the need for a better understanding of the interplay between viruses and the MGT. We review here how viruses, from ancient viruses that integrated the germline during evolution through old viruses (e.g., papillomaviruses originating from Neanderthals) and more modern sexually transmitted infections (e.g., simian zoonotic HIV) to emerging viruses (e.g., Ebola and Zika) take advantage of genital tract colonization for horizontal dissemination, viral persistence, vertical transmission, and endogenization. The MGT immune responses to viruses and the impact of these infections are discussed. We summarize the latest data regarding the sources of viruses in semen and the complex role of this body fluid in sexual transmission. Finally, we introduce key animal findings that are relevant for our understanding of viral infection and persistence in the human MGT and suggest future research directions.