Dual role of immune cells in the testis: Protective or pathogenic for germ cells?

Germline cell de novo mutations and potential effects of inflammation on germline cell genome stability

Uncontrolled pathogenic genome mutations in germline cells might impair adult fertility, lead to birth defects or even affect the adaptability of a species. Understanding the sources of DNA damage, as well as the features of damage response in germline cells are the overarching tasks to reduce the mutations in germline cells. With the accumulation of human genome data and genetic reports, genome variants formed in germline cells are being extensively explored. However, the sources of DNA damage, the damage repair mechanisms, and the effects of DNA damage or mutations on the development of germline cells are still unclear. Besides exogenous triggers of DNA damage such as irradiation and genotoxic chemicals, endogenous exposure to inflammation may also contribute to the genome instability of germline cells. In this review, we summarized the features of de novo mutations and the specific DNA damage responses in germline cells and explored the possible roles of inflammation on the genome stability of germline cells.

Acute murine-betacoronavirus infection impairs testicular steroidogenesis and the quality of sperm production

Although several testicular alterations promoted by coronavirus infection have been demonstrated, the extent, causes, and players of testicular pathogenesis are not totally understood. The present study aimed to investigate the short-term effects on male fertility of intranasally administered murine hepatitis virus strain 3 (MHV-3), a member of the genus Betacoronavirus, which causes a severe systemic acute infection. This mouse model might be used as a in vivo prototype for investigating the impact of betacoronavirus on the endocrine and exocrine testicular functions with the advantage to be performed in a biosafety level 2 condition. Herein, we performed virological, histopathological, and molecular studies regarding the testicular spermatogenesis and the spermatic quality analyses in an MHV-3-infected C57BL/6 mice. The main outcomes showed that MHV-3 infects mouse testis and induces a testicular inflammatory state, impairing the steroidogenic pathway. The infection led to several alterations in the testicular parenchyma, such as: seminiferous epithelium sloughing, retention of residual bodies, germ cell apoptosis, alterations in intercellular junction proteins, and worse spermatogenic parameters. Moreover, the levels of plasmatic testosterone as well as the quality of sperm production reduced. Therefore, the present data suggest that the viral/inflammatory impairment of the steroidogenic pathway and the consequent imbalance of androgen levels is critical in testicular pathology, disturbing the SC barrier function and the germ cell differentiation. Our study is important for comprehending the effects of beta coronavirus infections on testis function in order to develop treatments that could prevent virus-mediated male infertility.

Potential role of inducible nitric oxide synthase (iNOS) activity in testicular dysfunction following co-administration of alcohol and combination antiretroviral therapy (cART) in diabetic rats: an immunohistochemistry study

Diabetes, alcohol abuse, and combination antiretroviral therapy (cART) use have been reported to cause multi-organ complications via induction of oxidative stress and inflammation. Moreover, these are the most common factors implicated in male reproductive dysfunctions. This study evaluated testicular oxidative stress, inflammation, apoptosis, and germ cell proliferation in diabetic rats receiving alcohol or cART and their combination. Thirty adult male Sprague Dawley rats were divided into five groups, each consisting of six rats; control, diabetic only (DM), diabetic treated with alcohol (DM + A), diabetic treated with cART (DM + cART), and diabetic treated with both alcohol and cART (DM + A + cART). After 90 days of treatment, the rats were terminated, and the testes were extracted and processed for immunohistochemistry analysis for oxidative stress, inflammatory cytokines, apoptosis, and cell proliferation marker. In comparison to the control, oxidative stress markers, inducible nitric oxide synthase (iNOS), malondialdehyde (MDA), and 8-hydroxydeoxyguanosine (8-OHDG) increased significantly in all treated groups. Expression of testicular proinflammatory cytokines, interleukin-1β, and tumor necrosis factor-α was upregulated in all treated groups, but interleukin-6 was upregulated in DM, DM + cART, and DM + A + cART treated groups and was downregulated in the DM + A treated group. All treated animal groups showed an upregulation of apoptotic marker (caspase 3) and a downregulation of proliferation marker (Ki-67). However, Ki-67 staining intensity significantly increased in treated animals compared to the control. These findings suggest that diabetes, alcohol abuse, cART use, and their combination via iNOS activity upregulation can induce inflammation and oxidative stress in testicular tissue, stimulating germ cell apoptosis and proliferation inhibition leading to failure of spermatogenesis.

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.

A review on immunological aspects in male reproduction: An immune cells and cytokines

The male reproductive system, particularly the male gamete, offers a unique barrier to the immune system. The growing germ cells in the testis need to be shielded from autoimmune damage. Hence the testis has to establish and sustain an immune-privileged milieu. Sertoli cells create this safe space, protected by the blood-testis barrier. Cytokines are a type of immune reaction that can positively and negatively affect male reproductive health. Inflammation, disease, and obesity are just a few physiological conditions for which cytokines mediate signals. They interact with steroidogenesis, shaping the adrenals and testes to produce the hormones needed for survival. In particular pathological condition, including autoimmune disorders, contains high levels of the same cytokines in semen that play an essential role in the immunomodulation of the male gonad. This review focuses on understanding the immunological role of cytokines in the control and development of male reproduction. Also, in maintaining male reproductive health and diseases linked with their aberrant function in the testis.

Effect of Granulocyte Colony-Stimulating Factor on the Development of Spermatogenesis in the Adulthood of Juvenile AML Mice Model Treated with Cytarabine

Pediatric acute myeloid leukemia (AML) generally occurs de novo. The treatment of AML includes cytarabine (CYT) and other medications. The granulocyte-colony stimulating factor (GCSF) is used in the clinic in cases of neutropenia after chemotherapies. We show that the administration of GCSF in combination with CYT in AML-diagnosed mice (AML+CYT+GCSF) extended the survival of mice for additional 20 days. However, including GCSF in all treatment modalities does not affect the testis' weight or the histology of the seminiferous tubules (STs). We show that GCSF does not affect normal ST histology from AML-, CYT-, or (AML+CYT)-treated groups compared to the relevant treated group without GCSF 2, 4, and 5 weeks post-injection. However, when comparing the percentages of normal STs between the AML+CYT+GCSF-treated groups and those without GCSF, we observe an increase of 17%-42% in STs at 4 weeks and 5.5 weeks post-injection. Additionally, we show that the injection of GCSF into the normal, AML-alone, or CYT-alone groups, or in combination with AML, significantly decreases the percentage of STs with apoptotic cells compared to the relevant groups without GCSF and to the CT (untreated mice) only 2 weeks post-injection. We also show that injection of GCSF into the CT group increases the examined spermatogonial marker PLZF within 2 weeks post-injection. However, GCSF does not affect the count of meiotic cells (CREM) but decreases the post-meiotic cells (ACROSIN) within 4 weeks post-injection. Furthermore, GCSF not only extends the survival of the AML+CYT-treated group, but it also leads to the generation of sperm (1.2 ± 0.04 × 106/mL) at 5.5 weeks post-injection. In addition, we demonstrate that the injection of GCSF into the CT group increases the RNA expression level of IL-10 but not IL-6 compared to CT 2 weeks post-treatment. However, the injection of GCSF into the AML-treated group reverses the expression levels of both IL-10 and IL-6 to normal levels compared to CT 2 weeks post-injection. Thus, we suggest that the addition of GCSF to the regimen of AML after CYT may assist in the development of future therapeutic strategies to preserve male fertility in AML prepubertal patients.

SARS-CoV-2 Structural Proteins Modulated Blood-Testis Barrier-Related Proteins through Autophagy in the Primary Sertoli Cells

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) disrupts the blood-testis barrier (BTB), resulting in alterations in spermatogenesis. However, whether BTB-related proteins (such as ZO-1, claudin11, N-cadherin, and CX43) are targeted by SARS-CoV-2 remains to be clarified. BTB is a physical barrier between the blood vessels and the seminiferous tubules of the animal testis, and it is one of the tightest blood-tissue barriers in the mammalian body. In this study, we investigated the effects of viral proteins, via ectopic expression of individual viral proteins, on BTB-related proteins, the secretion of immune factors, and the formation and degradation of autophagosomes in human primary Sertoli cells. Our study demonstrated that ectopic expression of viral E (envelope protein) and M (membrane protein) induced the expressions of ZO-1 and claudin11, promoted the formation of autophagosomes, and inhibited autophagy flux. S (spike protein) reduced the expression of ZO-1, N-cadherin, and CX43, induced the expression of claudin11, and inhibited the formation and degradation of autophagosomes. N (nucleocapsid protein) reduced the expression of ZO-1, claudin11, and N-cadherin. All the structural proteins (SPs) E, M, N, and S increased the expression of the FasL gene, and the E protein promoted the expression and secretion of FasL and TGF-β proteins and the expression of IL-1. Blockage of autophagy by specific inhibitors resulted in the suppression of BTB-related proteins by the SPs. Our results indicated that SARS-CoV-2 SPs (E, M, and S) regulate BTB-related proteins through autophagy.

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.

Identification of biomarkers associated with macrophage infiltration in non-obstructive azoospermia using single-cell transcriptomic and microarray data

Background

Non-obstructive azoospermia (NOA) is a common clinical cause of male infertility. Research suggests that macrophages are linked to testicular function; however, their involvement in NOA remains unknown.

Methods

To evaluate the importance of macrophages infiltration in NOA and identify the macrophage-related biomarkers, the gene-expression microarray data GSE45885 and the single-cell transcriptomic data GSE149512 were utilized from the Gene Expression Omnibus (GEO). A single-sample gene set enrichment analysis (ssGSEA) was conducted to investigate immune cell proliferation. The Seurat package was used for the single-cell data analysis, and the limma package was used to identify the differentially expressed genes between the NOA and normal samples. Moreover, we conducted a weighted gene co-expression network analysis (WGCNA) to identify the macrophage-related key modules and genes, and conducted Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) analyses for the functional exploration. To identify the macrophage-related biomarkers, we conducted least absolute shrinkage and selection operator (LASSO) and support vector machine-recursive feature elimination (SVM-RFE) analyses. Real-time quantitative polymerase chain reaction (RT-qPCR) was used to verify the marker genes present in NOA.

Results

We confirmed that open reading frame 72 gene on chromosome 9 (C9orf72) [area under the curve (AUC) =0.861] and cartilage-associated protein (CRTAP) (AUC =0.917) were the hub genes of NOA, and the RT-qPCR analysis revealed the critical expression of both genes in NOA.

Conclusions

Through the combination of tissue transcriptomic and single-cell RNA-sequencing analyses, we concluded that macrophage infiltration is significant in different subtypes of NOA, and we hypothesized that C9orf72 and CRTAP play critical roles in NOA due to their high expression in macrophages.

SARS-CoV-2, COVID-19, and Reproduction: Effects on Fertility, Pregnancy, and Neonatal Life

Since its discovery in Wuhan, China, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread over the world, having a huge impact on people’s lives and health. The respiratory system is often targeted in people with the coronavirus disease 2019 (COVID-19). The virus can also infect many organs and tissues in the body, including the reproductive system. The consequences of the SARS-CoV-2 infection on fertility and pregnancy in hosts are poorly documented. Available data on other coronaviruses, such as severe acute respiratory syndrome (SARS-CoV) and Middle Eastern Respiratory Syndrome (MERS-CoV) coronaviruses, identified pregnant women as a vulnerable group with increased pregnancy-related complications. COVID-19 was also shown to impact pregnancy, which can be seen in either the mother or the fetus. Pregnant women more likely require COVID-19 intensive care treatment than non-pregnant women, and they are susceptible to giving birth prematurely and having their newborns admitted to the neonatal intensive care unit. Angiotensin converting enzyme 2 (ACE2), a key player of the ubiquitous renin-angiotensin system (RAS), is the principal host cellular receptor for SARS-CoV-2 spike protein. ACE2 is involved in the regulation of both male and female reproductive systems, suggesting that SARS-CoV-2 infection and associated RAS dysfunction could affect reproduction. Herein, we review the current knowledge about COVID-19 consequences on male and female fertility, pregnant women, and their fetuses. Furthermore, we describe the effects of COVID-19 vaccination on reproduction.

Sertoli Cell Immune Regulation: A Double-Edged Sword

The testis must create and maintain an immune privileged environment to protect maturing germ cells from autoimmune destruction. The establishment of this protective environment is due, at least in part, to Sertoli cells. Sertoli cells line the seminiferous tubules and form the blood-testis barrier (BTB), a barrier between advanced germ cells and the immune system. The BTB compartmentalizes the germ cells and facilitates the appropriate microenvironment necessary for spermatogenesis. Further, Sertoli cells modulate innate and adaptive immune processes through production of immunoregulatory compounds. Sertoli cells, when transplanted ectopically (outside the testis), can also protect transplanted tissue from the recipient’s immune system and reduce immune complications in autoimmune diseases primarily by immune regulation. These properties make Sertoli cells an attractive candidate for inflammatory disease treatments and cell-based therapies. Conversely, the same properties that protect the germ cells also allow the testis to act as a reservoir site for infections. Interestingly, Sertoli cells also have the ability to mount an antimicrobial response, if necessary, as in the case of infections. This review aims to explore how Sertoli cells act as a double-edged sword to both protect germ cells from an autoimmune response and activate innate and adaptive immune responses to fight off infections.

Histone H4 acetylation is dysregulated in active seminiferous tubules adjacent to testicular tumours

STUDY QUESTION

Is histone H4 acetylation (H4ac) altered in the seminiferous tubules of patients affected by testicular tumours?

SUMMARY ANSWER

A considerable dysregulation of H4ac was detected in the cells of the seminiferous tubules adjacent to testicular tumours of different aetiology and prior to any treatment, while no comparable alterations were observed in patients with disrupted spermatogenesis.

WHAT IS KNOWN ALREADY

Altered H4ac levels have been associated with a variety of testicular pathological conditions. However, no information has been available regarding potential alterations in the spermatogenic cells adjacent to the neoplasia in testicular tumour patients.

STUDY DESIGN, SIZE, DURATION

A retrospective analysis using testicular sections from 33 men aged between 21 and 74 years old was performed. Three study groups were defined and subjected to double-blind evaluation: a control group with normal spermatogenesis (n = 6), patients with testicular tumours (n = 18) and patients with spermatogenic impairments (n = 8). One additional sample with normal spermatogenesis was used as a technical internal control in all evaluations.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Immunohistochemistry against H4ac and, when needed, Placental-like alkaline phosphatase and CD117, was performed on testicular sections. The H4ac H-score, based on the percentage of detection and signal intensity, was used as the scoring method for statistical analyses. Protein expression data from the Human Protein Atlas were used to compare the expression levels of predicted secreted proteins from testicular tumours with those present in the normal tissue.

MAIN RESULTS AND THE ROLE OF CHANCE

We revealed, for the first time, a dramatic disruption of the spermatogenic H4ac pattern in unaffected seminiferous tubule cells from different testicular tumour patients prior to any antineoplastic treatment, as compared to controls (P < 0.05). Since no similar alterations were associated with spermatogenic impairments and the in silico analysis revealed proteins potentially secreted by the tumour to the testicular stroma, we propose a potential paracrine effect of the neoplasia as a mechanistic hypothesis for this dysregulation.

LIMITATIONS, REASONS FOR CAUTION

Statistical analyses were not performed on the hypospermatogenesis and Leydig cell tumour groups due to limited availability of samples.

WIDER IMPLICATIONS OF THE FINDINGS

To the best of our knowledge, this is the first report showing an epigenetic alteration in cells from active seminiferous tubules adjacent to tumour cells in testicular tumour patients. Our results suggest that, despite presenting spermatogenic activity, the global epigenetic dysregulation found in the testicular tumour patients could lead to molecular alterations of the male germ cells. Since testicular tumours are normally diagnosed in men at reproductive age, H4ac alterations might have an impact when these testicular tumour patients express a desire for fatherhood.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the European Union Marie Curie European Training Network actions and by grants to R.O. from the 'Ministerio de Economía y Competividad (Spain)' (fondos FEDER 'una manera de hacer Europa', PI13/00699, PI16/00346 and PI20/00936) and from EU-FP7-PEOPLE-2011-ITN289880. J.C. was supported by the Sara Borrell Postdoctoral Fellowship, Acción Estratégica en Salud, CD17/00109. J.C. is a Serra Húnter fellow (Universitat de Barcelona, Generalitat de Catalunya). F.B. has received grants from the Ministerio de Educación, Cultura y Deporte para la Formación de Profesorado Universitario (Spain) (FPU15/02306). A.d.l.I. is supported by a fellowship of the Ministerio de Economía, Industria y Competitividad (Spain) (PFIS, FI17/00224). M.J. is supported by the Government of Catalonia (Generalitat de Catalunya, pla estratègic de recerca i innovació en salut, PERIS 2016-2020, SLT002/16/00337). The authors have no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

N/A.

Understanding the Underlying Molecular Mechanisms of Meiotic Arrest during In Vitro Spermatogenesis in Rat Prepubertal Testicular Tissue

In vitro spermatogenesis appears to be a promising approach to restore the fertility of childhood cancer survivors. The rat model has proven to be challenging, since germ cell maturation is arrested in organotypic cultures. Here, we report that, despite a meiotic entry, abnormal synaptonemal complexes were found in spermatocytes, and in vitro matured rat prepubertal testicular tissues displayed an immature phenotype. RNA-sequencing analyses highlighted up to 600 differentially expressed genes between in vitro and in vivo conditions, including genes involved in blood-testis barrier (BTB) formation and steroidogenesis. BTB integrity, the expression of two steroidogenic enzymes, and androgen receptors were indeed altered in vitro. Moreover, most of the top 10 predicted upstream regulators of deregulated genes were involved in inflammatory processes or immune cell recruitment. However, none of the three anti-inflammatory molecules tested in this study promoted meiotic progression. By analysing for the first time in vitro matured rat prepubertal testicular tissues at the molecular level, we uncovered the deregulation of several genes and revealed that defective BTB function, altered steroidogenic pathway, and probably inflammation, could be at the origin of meiotic arrest.

High Throughput scRNA-Seq Provides Insights Into Leydig Cell Senescence Induced by Experimental Autoimmune Orchitis: A Prominent Role of Interstitial Fibrosis and Complement Activation

Leydig cells (Lc), located in the interstitial space of the testis between seminiferous tubules, produce 95% of testosterone in male individuals, which is pivotal for male sexual differentiation, spermatogenesis, and maintenance of the male secondary sex characteristics. Lc are prone to senescence in aging testes, resulting in compromised androgen synthesis capability upon aging. However, little is known about whether Lc undergo senescence in a chronic inflammatory environment. To investigate this question, mouse models of experimental autoimmune orchitis (EAO) were used, and Lc were analyzed by high throughput scRNA-Seq. Data were screened and analyzed by correlating signaling pathways with senescence, apoptosis, androgen synthesis, and cytokine/chemokine signaling pathways. EAO did induce Lc senescence, and Lc senescence in turn antagonized androgen synthesis. Based on the correlation screening of pathways inducing Lc senescence, a plethora of pathways were found to play potential roles in triggering Lc senescence during EAO, among which the Arf6 and angiopoietin receptor pathways were highly correlated with senescence signature. Notably, complement and interstitial fibrosis activated by EAO worsened Lc senescence and strongly antagonized androgen synthesis. Furthermore, most proinflammatory cytokines enhanced both senescence and apoptosis in Lc and spermatogonia (Sg) during EAO, and proinflammatory cytokine antagonism of the glutathione metabolism pathway may be key in inducing cellular senescence during EAO.

Testicular exosomes disturb the immunosuppressive phenotype of testicular macrophages mediated by miR-155-5p in uropathogenic Escherichia coli-induced orchitis

Male reproductive infections are known to shape the immunological homeostasis of the testes, leading to male infertility. However, the specific pathogenesis of these changes remains poorly understood. Exosomes released in the inflammatory microenvironment are important in communication between the local microenvironment and recipient cells. Here, we aim to identify the immunomodulatory properties of inflammatory testes-derived exosomes (IT-exos) and explore their underlying mechanisms in orchitis. IT-exos were isolated using a uropathogenic Escherichia coli (UPEC)-induced orchitis model and confirmed that IT-exos promoted proinflammatory M1 activation with increasing expression of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) in vitro. We further used small RNA sequencing to identify the differential miRNA profiles in exosomes and primary testicular macrophages (TMs) from normal and UPEC-infected testes, respectively, and identified that miR-155-5p was highly enriched in IT-exos and TMs from inflammatory testes. Further study of bone marrow derived macrophages (BMDMs) transfected with miR-155-5p mimic showed that macrophages polarized to proinflammatory phenotype. In addition, the mice that were administrated IT-exos showed remarkable activation of TM1-like macrophages; however, IT-exos with silencing miR-155-5p showed a decrease in proinflammatory responses. Overall, we demonstrate that miR-155-5p delivered by IT-exos plays an important role in the activation of TM1 in UPEC-induced orchitis. Our study provides a new perspective on the immunological mechanisms underlying inflammation-related male infertility.

The Importance of Tissue Sanctuaries and Cellular Reservoirs of HIV-1

Purpose of Review - There have been significant developments in the treatment of people living with HIV-1/AIDS with current antiretroviral therapies; however, these developments have not been able to achieve a functional or sterilizing cure for HIV-1. While there are multiple barriers, one such barrier is the existence of pharmacological sanctuaries and viral reservoirs where the concentration of antiretrovirals is suboptimal, which includes the gut-associated lymphoid tissue, central nervous system, lymph nodes, and myeloid cells. This review will focus on illustrating the significance of these sanctuaries, specific barriers to optimal antiretroviral concentrations in each of these sites, and potential strategies to overcome these barriers. Recent Findings - Research and studies have shown that a uniform antiretroviral distribution is not achieved with current therapies. This may allow for low-level replication associated with low antiretroviral concentrations in these sanctuaries/reservoirs. Many methods are being investigated to increase antiretroviral concentrations in these sites, such as blocking transporting enzymes functions, modulating transporter expression and nanoformulations of current antiretrovirals. While these methods have been shown to increase antiretroviral concentrations in the sanctuaries/reservoirs, no functional or sterilizing cure has been achieved due to these approaches. Summary - New methods of increasing antiretroviral concentrations at the specific sites of HIV-1 replication has the potential to target cellular reservoirs. In order to optimize antiretroviral distribution into viral sanctuaries/reservoirs, additional research is needed.

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.

Activation of C-C motif chemokine receptor 2 modulates testicular macrophages number, steroidogenesis, and spermatogenesis progression

The monocyte chemoattractant protein 1 (MCP-1) belongs to the CC chemokine family and acts in the recruitment of C-C motif chemokine receptor 2 (CCR2)-positive immune cell types to inflammation sites. In testis, the MCP-1/CCR2 axis has been associated with the macrophage population's functional regulation, which presents significant functions supporting germ cell development. In this context, herein, we aimed to investigate the role of the chemokine receptor CCR2 in mice testicular environment and its impact on male sperm production. Using adult transgenic mice strain that had the CCR2 gene replaced by a red fluorescent protein gene, we showed a stage-dependent expression of CCR2 in type B spermatogonia and early primary spermatocytes. Several parameters related to sperm production were reduced in the absence of CCR2 protein, such as Sertoli cell efficiency, meiotic index, and overall yield of spermatogenesis. Daily sperm production decreased by almost 40%, and several damages in the seminiferous tubules were observed. Significant reduction in the expression of important genes related to the Sertoli cell function (Cnx43, Vim, Ocln, Spna2) and meiosis initiation (Stra8, Pcna, Prdm9, Msh5) occurred in comparison to controls. Also, the number of macrophages significantly decreased in the absence of CCR2 protein, along with a disturbance in Leydig cell steroidogenic activity. In summary, our results show that the non-activation of the MCP-1/CCR2 axis disturbs the testicular homeostasis, interfering in macrophage population, meiosis initiation, blood-testis barrier function, and androgen synthesis, leading to the malfunction of seminiferous tubules, decreased testosterone levels, defective sperm production, and lower fertility index.

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.

Interleukin-6 deficiency modulates testicular function by increasing the expression of suppressor of cytokine signaling 3 (SOCS3) in mice

Several cytokines have been reported to participate in spermatogenesis, including interleukin-6 (IL6). However, not many studies have been conducted on the loss of Il6 on the male reproductive tract. Nonetheless, there is considerable knowledge regarding the pathological and physiological role of IL6 on spermatogenesis. In this way, this study evaluated the impact of Il6 deficiency on mice testicles in the absence of infection or inflammation. We showed that Il6 deficiency increases daily sperm production, the number of spermatids, and the testicular testosterone and dihydrotestosterone levels. Besides that, mice with a deleted Il6 (IL6KO) showed increased testicular SOCS3 levels, with no changes in pJAK/JAK and pSTAT3/STAT3 ratios. It is worth noting that the aforementioned pathway is not the only pathway to up-regulate SOCS3, nor is it the only SOCS3 target, thus proposing that the increase of SOCS3 in the testis occurs independently of the JAK-STAT signaling in IL6KO mice. Therefore, we suggest that the lack of Il6 drives androgenic production by increasing SOCS3 in the testis, thus leading to an increase in spermatogenesis.

Integrating miRNA and mRNA Profiling to Assess the Potential miRNA-mRNA Modules Linked With Testicular Immune Homeostasis in Sheep

Beyond its well-known role in spermatogenesis and androgen production, mammalian testes are increasingly recognized as an immune-privileged organ for protecting autoantigenic germ cells, especially meiotic and postmeiotic germ cells, from systemic immune responses. Despite its importance, the molecular mechanisms underlying this regulation in mammals, including sheep, are far from known. In this study, we searched for the genes associated with testicular immune privilege and assessed their possible modulating mechanisms by analyzing systematic profiling of mRNAs and miRNAs on testicular tissues derived from prepubertal and postpubertal Tibetan sheep acquired by RNA sequencing. We identified 1,118 differentially expressed (DE) mRNAs associated with immunity (245 increased mRNAs and 873 decreased mRNAs) and 715 DE miRNAs (561 increased miRNAs and 154 decreased miRNAs) in postpubertal testes compared with prepuberty. qPCR validations for 20 DE mRNAs and 16 miRNAs showed that the RNA-seq results are reliable. By using Western blot, the postpubertal testes exhibited decreased protein abundance of CD19 and TGFBR2 (two proteins encoded by DE mRNAs) when compared with prepuberty, consistent with mRNA levels. The subsequent immunofluorescent staining showed that the positive signals for the CD19 protein were observed mainly in Sertoli cells and the basement membrane of pre- and postpubertal testes, as well as the prepubertal testicular vascular endothelium. The TGFBR2 protein was found mostly in interstitial cells and germ cells of pre- and postpubertal testes. Functional enrichment analysis indicated that DE mRNAs were mainly enriched in biological processes or pathways strongly associated with the blood–testis barrier (BTB) function. Many decreased mRNAs with low expression abundance were significantly enriched in pathways related to immune response. Also, multiple key miRNA-target negative correlation regulatory networks were subsequently established. Furthermore, we verified the target associations between either oar-miR-29b or oar-miR-1185-3p and ITGB1 by dual-luciferase reporter assay. Finally, a putative schematic model of the miRNA-mRNA-pathway network mediated by immune homeostasis-related genes was proposed to show their potential regulatory roles in sheep testicular privilege. Taken together, we conclude that many immune-related genes identified in this study are negatively regulated by potential miRNAs to participate in the homeostatic regulation of testicular immune privilege of sheep by sustaining BTB function and inhibiting immune responses under normal physiological conditions. This work offers the first global view of the expression profiles of miRNAs/mRNAs involved in sheep testicular immune privilege and how the genes potentially contribute to immune-homeostatic maintenance.

Hypertension and reproductive dysfunction: a possible role of inflammation and inflammation-associated lymphangiogenesis in gonads

Hypertension is one of the most prevalent diseases that leads to end organ damage especially affecting the heart, kidney, brain, and eyes. Numerous studies have evaluated the association between hypertension and impaired sexual health, in both men and women. The detrimental effects of hypertension in men includes erectile dysfunction, decrease in semen volume, sperm count and motility, and abnormal sperm morphology. Similarly, hypertensive females exhibit decreased vaginal lubrication, reduced orgasm, and several complications in pregnancy leading to fetal and maternal morbidity and mortality. The adverse effect of hypertension on male and female fertility is attributed to hormonal imbalance and changes in the gonadal vasculature. However, mechanistic studies investigating the impact of hypertension on gonads in more detail on a molecular basis remain scarce. Hence, the aim of the current review is to address and summarize the effects of hypertension on reproductive health, and highlight the importance of research on the effects of hypertension on gonadal inflammation and lymphatics.

Unraveling Stage-Dependent Expression Patterns of Circular RNAs and Their Related ceRNA Modulation in Ovine Postnatal Testis Development

Circular RNAs (circRNAs) have been shown to function in the reproductive systems including testis. However, their expression, as well as function in testicular development of sheep remain undefined. Herein, we performed RNA sequencing to reveal circRNA temporal expression patterns in testes of Tibetan sheep from different stages of maturation (3M, 3-month-old; 1Y, 1-year-old; 3Y, 3-year-old). A total of 3,982, 414, and 4,060 differentially expressed (DE) circRNAs were uncovered from 3M vs 1Y, 1Y vs 3Y, and 3M vs 3Y, respectively. Functional enrichment assessment indicated that the source genes of DE circRNAs were primarily engaged in spermatogenesis and testicular immune privilege including blood-testis barrier (BTB). We subsequently constructed the core circRNA-miRNA-mRNA interaction network for genes related to testicular function, such as spermatogenesis, germ cell development, BTB, and cell cycle/meiosis. Furthermore, we validated the target associations between either circ_024949, circ_026259 or IGF1, and oar-miR-29b in this network, and revealed their similar expression signatures in developmental testes that they were extensively expressed in germ cells, Leydig cells, and Sertoli cells, thus suggesting their broad functions in the functional maintenance of Leydig cells and Sertoli cells, as well as the development and maturation of male germ cells. Meanwhile, circ_026259 was shown to promote IGF1 expression through inhibition of oar-miR-29b in sheep Sertoli cells. This work gives the first global view for the expression and regulation of circRNAs in sheep testis, which will be helpful for providing new insights into the molecular mechanism of ovine testis function.

Does SARS-CoV-2 Threaten Male Fertility?

In the continuing COVID-19 pandemic, one of the most important concerns in reproductive health is the issue of male fertility of recovered patients. In this study, we discuss the potential mechanisms that justify the possible impact of COVID-19 on male fertility. The main point of entry of SARS-CoV-2 into the host cells appears to be through the viral spike protein which permits entry into cells via the angiotensin-converting enzyme 2 (ACE2 receptor). In human testes, ACE2 is enriched in Sertoli and Leydig cells and spermatogonia. Also, it seems that there is a mild or severe cytokine storm in patients with severe COVID-19, and such changes may affect fertility. It should also be mentioned that the orchitis caused by the SARS-CoV-2 virus may have an important impact on fertility. Prolonged and high fever may lead to changes in testicular temperature and destroy germ cells. In general, there is little evidence for a definite conclusion, but there are facts that suggest that COVID-19 may affect male fertility. It is prudent for men of reproductive age who have recovered from COVID-19 to be evaluated for the presence of the virus in semen and fertility-related items. There is an urgent need to conduct quality studies on, in particular, the long-term effects of COVID-19 on the fertility of recovered males.

Evaluation of testicular structure in mice after exposure to environmentally relevant doses of manganese during critical windows of development

Despite being an essential trace element with great importance for vital metabolic activities, the manganese (Mn) can also cause damage to organ systems. However, data on the effect of this metal on the male reproductive system are limited, especially using relevant doses to human exposure. The present study aimed to evaluate and compare the effects of Mn exposure on the testicular structure of mice. Three experiments were conducted: (I) direct exposure to realistic doses (0.013, 0.13, and 1.3 mg/kg/day of MnCl₂); (II) parental and direct exposure to realistic doses (as in experiment I), where the animals were exposed during intrauterine development and from lactation until reproductive maturity; (III) direct exposure to high doses (15, 30, and 60 mg/kg/day of MnCl₂). Biometric, histopathological, histomorphometric and stereological parameters of the testis were evaluated, in addition to sperm morphology. Bioinformatic analyses were performed to identify potential Mn binding sites in 3β-HSD and P450ssc, as well as their protein-protein interaction network. The results obtained were compared using the integrated biomarker response index (IBR). There was an increase of seminiferous tubules pathologies in all experimental conditions tested, with effects on tubular volume, as well as a reduction in tubular diameter. The IBR analyses showed that parental and direct exposure had a significant negative effect on the testicular structure due to the exposure of this metal to sensitive periods of animal development. This study suggests that Mn has the potential to alter the morphological parameters of the testes, affecting the spermatogenesis in mice.

Regulation of Human Spermatogenesis

Human spermatogenesis (HS) is an intricate network of sequential processes responsible for the production of the male gamete, the spermatozoon. These processes take place in the seminiferous tubules (ST) of the testis, which are small tubular structures considered the functional units of the testes. Each human testicle contains approximately 600-1200 STs [1], and are capable of producing up to 275 million spermatozoa per day [2].

T Lymphocytes and Testicular Immunity: A New Insight into Immune Regulation in Testes

The immune privilege of the testes is necessary to prevent immune attacks to gamete-specific antigens and paternal major histocompatibility complex (MHC) antigens, allowing for normal spermatogenesis. However, infection and inflammation of the male genital tract can break the immune tolerance and represent a significant cause of male infertility. Different T cell subsets have been identified in mammalian testes, which may be involved in the maintenance of immune tolerance and pathogenic immune responses in testicular infection and inflammation. We reviewed the evidence in the published literature on different T subtypes (regulatory T cells, helper T cells, cytotoxic T cells, γδ T cells, and natural killer T cells) in human and animal testes that support their regulatory roles in infertility and the orchitis pathology. While many in vitro studies have indicated the regulation potential of functional T cell subsets and their possible interaction with Sertoli cells, Leydig cells, and spermatogenesis, both under physiological and pathological processes, there have been no in situ studies to date. Nevertheless, the normal distribution and function of T cell subsets are essential for the immune privilege of the testes and intact spermatogenesis, and T cell-mediated immune response drives testicular inflammation. The distinct function of different T cell subsets in testicular homeostasis and the orchitis pathology suggests a considerable potential of targeting specific T cell subsets for therapies targeting chronic orchitis and immune infertility.

Successful activation of rat T lymphocytes by sperm specific antigens in vitro

Autoimmune orchitis is a condition related to cellular immunity. A disease model involving transfer of T lymphocytes activated by known antigens would be useful for defining pathogenical molecules. Since no method for activating rat T cells using specific antigens is available, we started the study to develop the method. T cells were collected from draining lymph nodes of immunized rats, then co-cultured with syngeneic splenocytes as antigen-presenting cells (APC) in antigen-supplemented medium (= stimulation). The cells were then incubated in medium without antigens and APC (= resting). Repetitive stimulation and resting increased the number of the T cells more than 100-fold. The antigen-specific activation was demonstrated by cell proliferation assay and ELISA assay for interferon gamma. Flow cytometry revealed that > 95% of the cells expressed tumor necrosis factor alpha, a cytokine responsible for autoimmune orchitis. The present method will provide a new procedure to evaluate antigenicity of sperm molecules.

Tumor-associated macrophages derived from cancer stem cells

Macrophages are the most abundant immune cells in the microenvironment of solid tumors. The present study displayed histological and immunohistochemical analyses of a malignant tumor model developed from cancer stem cells (CSCs) converted from human induced pluripotent stem cells (hiPSCs) in a cancer microenvironment prepared from the conditioned medium (CM) of a pancreatic cancer cell line. We focused on the localization and the origin of tumor-associated macrophages (TAMs), To the best of our knowledge this may be the first study to suggest the potential differentiation of CSCs to TAMs. hiPSCs were converted into CSCs in the presence of CM from PK8 cells. CSCs were then transplanted in vivo and formed primary tumors. Primary cultures for these tumors were serially transplanted again to obtain secondary tumors. Secondary tumors exhibited histopathological features of malignancy. Cells derived from tumors maintained the expression of endogenous stemness markers and pancreatic CSCs markers. Simultaneously, high immunoreactivity to anti-mouse CD68, anti-human CD68, CD206 and CD11b antibodies were detected revealing that the tumor tissue derived from CSCs was enriched for macrophages which can originate from both human and mouse cells. The model of CSCs highlighted the possibility of CSCs to differentiate into TAMs.

Effect of ketotifen fumarate on experimental autoimmune orchitis and torsion of the spermatic cord

The aim of this work was to study effects of ketotifen fumarate (KF) on prevention of tissue damage in testes of rats with experimental autoimmune orchitis (EAO) and on the contralateral testis in a model of prolonged testicular cord torsion (TCT). Rats with EAO or TCT were injected intraperitoneally once daily with KF or saline solution (vehicle group). Incidence and severity of testicular damage were evaluated by histopathology using an EAO score or a Johnsen score. Mast cells (MC) were identified by histochemistry and quantified. In EAO model, KF significantly reduced severity of histopathological testicular damage compared to rats in the vehicle group. KF also reduced the number of testicular MC compared to vehicle group. Similarly, in TCT model, multifocal damage of the contralateral testis was observed 30 days after testicular torsion characterized by sloughing of the germinal epithelium, seminiferous tubule atrophy, and interstitial edema. Focal signs of inflammation and fibrosis of seminiferous tubular walls were also observed. In contrast, sections of contralateral testis of rats injected with KF and killed 30 days after surgery showed normal histological features. A significant decrease in the number of MC was observed in rats treated with KF compared to untreated animals. In conclusion, we demonstrated that treatment with KF reduced testicular inflammatory process and MC infiltrates in both EAO and TCT models. The results suggest a promising treatment for infertile male patients with testicular pathologies associated with inflammation and germ cell loss.

Multiple Expression Assessments of ACE2 and TMPRSS2 SARS-CoV-2 Entry Molecules in the Urinary Tract and Their Associations with Clinical Manifestations of COVID-19

Background

Since December 2019, the novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), first spread quickly in Wuhan, China, then globally. Based on previously published evidence, ACE2 and TMPRSS2 are both pivotal entry molecules that enable cellular infection by SARS-CoV-2. Also, increased expression of pro-inflammatory cytokines, or a “cytokine storm,” is associated with multiple organ dysfunction syndrome often observed in critically ill patients.

Methods

We investigated the expression pattern of ACE2 and TMPRSS2 in major organs in the human body, especially in specific disease conditions. Multiple sequence alignment of ACE2 in different species was used to explain animal susceptibility. Moreover, the cell-specific expression patterns of ACE2 and cytokine receptors in the urinary tract were assessed using single-cell RNA sequencing (scRNA-seq). Additional biological relevance was determined through Gene Set Enrichment Analysis (GSEA) using an ACE2-specific signature.

Results

Our results revealed that ACE2 and TMPRSS2 were highly expressed in genitourinary organs. ACE2 was highly and significantly expressed in the kidney among individuals with chronic kidney diseases or diabetic nephropathy. In single cells, ACE2 was primarily enriched in gametocytes in the testis and renal proximal tubules. The receptors for pro-inflammatory cytokines, especially IL6ST, were notably concentrated in endothelial cells, macrophages, spermatogonial stem cells in the testis, and renal endothelial cells, which suggested the occurrence of alternative damaging autoimmune mechanisms.

Conclusion

This study provided new insights into the pathogenic mechanisms of SARS-CoV-2 that underlie the clinical manifestations observed in the human testis and kidney. These observations might substantially facilitate the development of effective treatments for this rapidly spreading disease.

Pathomechanisms of Autoimmune Based Testicular Inflammation

Infection and inflammation of the male reproductive tract are relevant causes of infertility. Inflammatory damage occurs in the special immunosuppressive microenvironment of the testis, a hallmark termed testicular immune privilege, which allows tolerance to neo-antigens from developing germ cells appearing at puberty, long after the establishment of systemic immune tolerance. Experimental autoimmune orchitis (EAO) is a well-established rodent model of chronic testicular inflammation and organ specific autoimmunity that offers a valuable in vivo tool to investigate the pathological and molecular mechanisms leading to the breakdown of the testicular immune privilege. The disease is characterized by the infiltration of the interstitium by immune cells (mainly macrophages, dendritic cells, and T cells), formation of autoantibodies against testicular antigens, production of pro-inflammatory mediators such as NO, MCP1, TNFα, IL6, or activins and dysregulation of steroidogenesis with reduced levels of serum testosterone. EAO leads to sloughing of germ cells, atrophic seminiferous tubules and fibrotic remodeling, parameters all found similarly to changes in human biopsies from infertile patients with inflammatory infiltrates. Interestingly, testosterone supplementation during the course of EAO leads to expansion of the regulatory T cell population and inhibition of disease development. Knowledge of EAO pathogenesis aims to contribute to a better understanding of human testicular autoimmune disease as an essential prerequisite for improved diagnosis and treatment.

Immune Cell Subtypes and Their Function in the Testis

Immunoregulation in the testis is characterized by a balance between immuno-suppression (or immune privilege) and the ability to react to infections and inflammation. In this review, we analyze the phenotypes of the various immune cell subtypes present in the testis, and how their functions change between homeostatic and inflammatory conditions. Starting with testicular macrophages, we explore how this heterogeneous population is shaped by the testicular microenvironment to ensure immune privilege. We then describe how dendritic cells exhibit a tolerogenic status under normal conditions, but proliferate, mature and then stimulate effector T-cell expansion under inflammatory conditions. Finally, we outline the two T-cell populations in the testis: CD4⁺/CD8⁺ αβ T cells and CD4⁺/CD8⁺ Foxp3⁺ regulatory T cells and describe the distribution and function of mast cells. All these cells help modulate innate immunity and regulate the immune response. By improving our understanding of immune cell behavior in the testis under normal and inflammatory conditions, we will be better placed to evaluate testis impairment due to immune mechanisms in affected patients.

Redox metabolism modulation as a mechanism in SSRI toxicity and pharmacological effects

Depressive disorders are amongst the greatest mental health challenges, with an increasing number of patients being diagnosed each year. Though it has not yet been fully elucidated, redox metabolism imbalances and oxidative stress seem to play a major role in the pathogenesis of depressive disorders. Selective serotonin reuptake inhibitors (SSRIs) are the most prescribed antidepressants, considered to have a better tolerability. However, several adverse effects have been reported and the mechanisms involved in their pharmacological activity are not entirely understood. SSRIs have been shown to influence the redox metabolism, which could be involved in their toxicity and pharmacological effects. A comparative analysis of published in vivo and in vitro data regarding the activity of SSRIs on the redox metabolism pathways has been performed in this paper, with an emphasis on mechanistical aspects. Furthermore, a comparison between oxidative stress biomarker levels reported by different studies was attempted. The reviewed data point towards both pro- and antioxidant effects of SSRIs, dependent on tissue/cell type and dose/concentration, suggest a redox modulating potential of these compounds. In hepatic and testicular tissue, the majority of reviewed studies reported pro-oxidant effects, with possible implications towards the hepatotoxicity and sexual dysfunction that were reported following SSRI treatment; while in brain, the most common findings were antioxidant effects that could partially explain their antidepressant activity. However, given the heterogeneity of the reviewed data, further research is needed to fully understand the impact of SSRIs on redox metabolism and its implications.

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.

Genetic Landscape of Nonobstructive Azoospermia and New Perspectives for the Clinic

Nonobstructive azoospermia (NOA) represents the most severe expression of male infertility, involving around 1% of the male population and 10% of infertile men. This condition is characterised by the inability of the testis to produce sperm cells, and it is considered to have an important genetic component. During the last two decades, different genetic anomalies, including microdeletions of the Y chromosome, karyotype defects, and missense mutations in genes involved in the reproductive function, have been described as the primary cause of NOA in many infertile men. However, these alterations only explain around 25% of azoospermic cases, with the remaining patients showing an idiopathic origin. Recent studies clearly suggest that the so-called idiopathic NOA has a complex aetiology with a polygenic inheritance, which may alter the spermatogenic process. Although we are far from a complete understanding of the molecular mechanisms underlying NOA, the use of the new technologies for genetic analysis has enabled a considerable increase in knowledge during the last years. In this review, we will provide a comprehensive and updated overview of the genetic basis of NOA, with a special focus on the possible application of the recent insights in clinical practice.

Therapeutic prospects of hydroxytyrosol on experimentally induced diabetic testicular damage: potential interplay with AMPK expression

Male reproductive dysfunction represents one of the overlooked consequences of diabetes that still deserve more scientific attention. We designed this study to explore the therapeutic potential of hydroxytyrosol (HT) on diabetic testicular damage and to investigate its relationship with adenosine monophosphate-activated protein kinase (AMPK) expression. In this context, 30 adult male Wistar rats were utilized and subdivided into control, diabetic and HT-treated diabetic groups. Testicular sections were prepared for histopathological examination and immunohistochemical detection of 8-hydroxy-2'-deoxyguanosine, Sertoli cell vimentin, myoid cell α-SMA, androgen receptors and caspase-3. We also assessed oxidative enzymatic and lipid peroxidation biochemical profiles, sperm count, morphology and motility. Real-time PCR of AMPK expression in tissue homogenate was performed. We observed that HT restored testicular histopathological structure and significantly reduced oxidative DNA damage and the apoptotic index. The HT-treated group also exhibited significantly higher Sertoli cell vimentin, myoid cell α-SMA and androgen receptor immune expression than the diabetic group. A rescue of the oxidative enzymatic activity, lipid peroxidation profiles, sperm count, morphology and motility to control levels was also evident in the HT-treated group. Significant upregulation of AMPK mRNA expression in the HT-treated group clarified the role of AMPK as an underlying molecular interface of the ameliorative effects of HT. We concluded that HT exhibited tangible antioxidant and antiapoptotic impacts on the testicular cytomorphological and immunohistochemical effects of experimentally induced diabetes. Furthermore, AMPK has an impactful role in the molecular machinery of these effects.

Fluoride Induces Autoimmune Orchitis Involved with Enhanced IL-17A Secretion in Mice Testis

Fluoride (F) widely exists in the water and food. Recent studies reported that F induced testicular toxicity via inflammation reaction. This study was aimed to explore the mechanism of F-induced inflammation in testis. 100 healthy male mice (BALB/cJ strain) were randomly divided into five groups including: control, experimental autoimmune orchitis (EAO), and three F groups (25, 50, and 100 mg/L sodium fluoride (NaF)). After 150 d, the results showed a significant increase in testicular cytokines levels including of IL-17A, IL-6, IFN-γ, and TNF-α in NaF and EAO groups compared with control group. Interestingly, the presence of specific antisperm autoantibodies in antitesticular autoantibodies and the notable recruitment of immunocyte (T cells and dendritic cells) were also observed in NaF and EAO groups. In addition, findings showed that in NaF and EAO groups macrophages and T cells both significantly secreted IL-17A, and the protein and mRNA levels of cytokines (IL-6 and TGF-β) were significantly increased. From these results, it can be concluded that autoimmune orchitis and IL-17A are implicated in F-induced testicular inflammation.

β-adrenergic receptors in the up-regulation of COX2 expression and prostaglandin production in testicular macrophages: Possible relevance to male idiopathic infertility

Catecholaminergic neuronal elements (CNE) and macrophages (MACs) are increased in testes of patients with idiopathic infertility. Now, we describe an anatomical proximity between CNE and MACs, expression of specific α- and β-adrenergic receptors (ADRs) subtypes in MACs, and a positive correlation between the number of MACs and cyclooxygenase (COX2) expression - key enzyme in prostaglandin (PG) synthesis and an inflammatory marker - in testes of infertile men. To examine a potential effect of adrenergic input on COX2 expression, we used two additional experimental models: non-testicular human MACs (THP1 cell line) and non-human testicular MACs purified from adult Syrian hamsters. We found that epinephrine and norepinephrine up-regulate COX2 expression and PGD2 production through β1-and β2-ADRs. Our results demonstrate the existence of a yet unknown link between CNE and MACs in the human testis that could trigger inflammation and tissue homeostatic dysregulation associated with pathogenesis or maintenance of infertility states.

Role of indoleamine 2,3-dioxygenase in testicular immune-privilege

Male meiotic germ cell including the spermatozoa represent a great challenge to the immune system, as they appear long after the establishment of normal immune tolerance mechanisms. The capacity of the testes to tolerate autoantigenic germ cells as well as survival of allogeneic organ engrafted in the testicular interstitium have led to consider the testis an immunologically privileged site. Disruption of this immune privilege following trauma, tumor, or autoimmune orchitis often results in male infertility. Strong evidence indicates that indoleamine 2,3-dioxygenase (IDO) has been implicated in fetal and allograft tolerance, tumor immune resistance, and regulation of autoimmune diseases. IDO and tryptophan 2,3-dioxygenase (TDO) catalyze the same rate-limiting step of tryptophan metabolism along a common pathway, which leads to tryptophan starvation and generation of catabolites collectively known as kynurenines. However, the relevance of tryptophan metabolism in testis pathophysiology has not yet been explored. Here we assessed the in vivo role of IDO/TDO in experimental autoimmune orchitis (EAO), a model of autoimmune testicular inflammation and immunologically impaired spermatogenesis. EAO was induced in adult Wistar rats with testicular homogenate and adjuvants. Control (C) rats injected with saline and adjuvants and normal untreated rats (N) were also studied. mRNA expression of IDO decreased in whole testes and in isolated Sertoli cells during EAO. TDO and IDO localization and level of expression in the testis were analyzed by immunostaining and Western blot. TDO is expressed in granulomas from EAO rats, and similar protein levels were observed in N, C, and EAO groups. IDO was detected in mononuclear and endothelial cells and reduced IDO expression was detected in EAO group compared to N and C rats. This phenomenon was concomitant with a significant reduction of IDO activity in EAO testis measured by tryptophan and kynurenine concentrations (HPLC). Finally, in vivo inhibition of IDO with 1-methyl-tryptophan increased severity of the disease, demonstrating down regulation of IDO-based tolerance when testicular immune regulation was disrupted. We present evidence that an IDO-based mechanism is involved in testicular immune privilege.

Viral threat to male fertility

The detrimental effects of Zika virus (ZIKV) infection on mouse testicular functions have reminded a viral threat to male fertility. A broad range of virus families has tropism for male reproductive system, particularly the testes. Certain virus types of these viruses, such as mumps virus and human immunodeficiency virus (HIV), may severely damage the testes and consequently lead to male infertility. ZIKV has been recently found to damage testicular functions and lead to male infertility in mice. Many other viruses also have detrimental effects on host reproduction. Public attention has been paid to sexually transmitted viruses, such as HIV and hepatitis B and C viruses in humans and likewise in economically important farm animals. This article provides an overview on main viruses affecting the male reproductive system and their detrimental effects on fertility, and outlines some important issues for future study.

Growing Trans-Species Islets in Tumor Extract-Remodeled Testicles

Although pancreatic islet transplantation holds promise for the treatment of type I diabetes, its application has been significantly hampered by transplant rejection. Here, an approach is demonstrated to support trans-species islet beta cells from a rat to grow and function in the body of a mouse host while overcoming graft rejection. This approach, which builds on remodeling of the mouse testicle by local injection of a tumor homogenate, establishes an immunosuppressive and proregenerative niche in the testicle. This remodeling proves necessary and effective in shaping the testicle into a unique site to accommodate xenograft cells. Rat pancreatic beta cells-from both the insulinoma (cancer cells) and pancreatic islet (normal tissue)-survive, grow, and form a desirable morphology in the remodeled mouse testicle. Notably, when hyperglycemia is induced in the host body, these xenografts secrete insulin to regulate the blood glucose level in mice for as long as 72 days. Furthermore, no graft rejection, acute inflammation, or safety risks are observed throughout the study. In summary, it is demonstrated that the growth of xenogeneic insulinoma cells in a mouse testicle might serve as an alternative approach for islet transplantation.

Protective effects of fermented goat milk on genomic stability, oxidative stress and inflammatory signalling in testis during anaemia recovery

Oxidative stress is a harmful factor for male reproductive function, and a major cause of infertility. On the other hand, fermented goat milk has positive effects on anemia recovery and mineral metabolism. This study evaluated the effect of feeding rats with fermented milks during anaemia recovery on molecular mechanisms linked to oxidative stress and inflammatory signalling in rats reproductive system. Forty male Wistar rats were placed on a pre-experimental period of 40 days (control group, receiving normal-Fe diet and Fe-deficient group, receiving low-Fe diet). Lately, rats were fed with fermented goat or cow milk-based diets during 30 days. After feeding the fermented milks, Total antioxidant status (TAS) and non-esterified fatty acids (NEFA) increased and 8-hydroxy-2’-deoxyguanosine (8-OHdG), 15-F2t-isoprostanes and thiobarbituric acid reactive substances (TBARS) decreased in testis. DNA oxidative damage in testis germ cells was lower with fermented goat milk. Fermented goat milk reduced IL-6 and TNF-α in control animals, increasing INF-γ in control and anaemic rats. NRF2 and PGC-1α protein levels increased in testis after fermented goat milk consumption in control and anaemic rats. Fermented goat milk also increased TAS and decreased oxidative damage, protecting the main testis cell bioconstituents (lipids, proteins, DNA, prostaglandins) from oxidative damage and reduced inflammatory activity, preventing injuries to testis germinal epithelium. Fermented goat milk enhanced lipolysis, fatty acids degradation and immune response, attenuating inflammatory signalling, representing a positive growth advantage for testicular cells.

Retinoic acid receptor signaling is necessary in steroidogenic cells for normal spermatogenesis and epididymal function

Spermatogenesis in mammals is a very complex, highly organized process, regulated in part by testosterone and retinoic acid (RA). Much is known about how RA and testosterone signaling pathways independently regulate this process, but there is almost no information regarding whether these two signaling pathways directly interact and whether RA is crucial for steroidogenic cell function. This study uses a transgenic mouse line that expresses a dominant-negative form of RA receptor α (RAR-DN) and the steroidogenic cell-specific Cre mouse line, Cyp17iCre, to generate male mice with steroidogenic cells unable to perform RA signaling. Testes of mutant mice displayed increased apoptosis of pachytene spermatocytes, an increased number of macrophages in the interstitium and a loss of advanced germ cells. Additionally, blocking RA signaling in Leydig cells resulted in increased permeability of the blood-testis barrier, decreased levels of the steroidogenic enzyme cytochrome P450 17a1 and decreased testosterone levels. Surprisingly, the epididymides of the mutant mice also displayed an abnormal phenotype. This study demonstrates that RA signaling is required in steroidogenic cells for their normal function and, thus, for male fertility.

Association Between Nonalcoholic Fatty Liver Disease and Severe Male Reproductive Organ Impairment (Germinal Epithelial Loss): Study on a Mouse Model and on Human Patients

Metabolic syndrome (MS) has been associated with testicular damage. Nonalcoholic fatty liver disease (NAFLD) is a multisystemic disease that affects different organs, but its effect on the testes is unknown. A study analyzing germ cell involvement on BALB/c mice was carried out. A parallel comparative study was conducted that investigated alterations in the germinal epithelium of male humans that died from an unrelated acute event. The complete medical histories and histologic samples of the thoracic aorta, liver tissue, and testicular tissue from the deceased subjects were collected. The degree of germinal epithelial loss (DGEL) was evaluated and the clinical and histologic data were compared between individuals with and without NAFLD. The only metabolic or morphologic variable that caused a significant difference in the DGEL, in both the animal model and humans, was the presence of liver steatosis. The percentage of steatosis was also correlated with the percentage of the DGEL. In humans, steatosis (greater than 20%) increased the risk 12-fold for presenting with a severe DGEL (OR: 12.5; 95% CI [1.2, 128.9]; p = .03). There was no association with age above 50 years or MS components. Steatosis grade was also correlated with atherosclerosis grade. NAFLD was a strongly associated factor implicated in severe DGEL, as well as the testis was identified as a probable target organ for damage caused by the disease. This finding could result in the search for new approach strategies in the management of men with fertility problems. Further studies are required to confirm these results.

Regionally distinct patterns of STAT3 phosphorylation in the seminiferous epithelia of mouse testes

In mouse testes, Sertoli cells support the continuous process of spermatogenesis, which is dependent on seminiferous epithelial cycles along the longitudinal axis of the seminiferous tubule. Sertoli cell function is modulated partly by local cytokines and/or growth factors derived from adjacent tissues such as blood vessels, macrophages, rete testis, etc. However, the spatial activation patterns by local signals in vivo remain unclear. In this study, we focused on Signal Transducers and Activators of Transcription (STAT) signaling in Sertoli cells, because STAT is a major crucial cytokine transducer for somatic cyst cell regulation in Drosophila testis niches. In mouse testes, STAT3 was ubiquitously expressed in Sertoli cells throughout the seminiferous tubules. Phosphorylated STAT3 (p-STAT3) was predominantly observed in the Sertoli cells within the valve-like structure adjacent to the rete testis (i.e., the Sertoli valve [SV]) in the terminal segment of the proximal seminiferous tubules. In the distal seminiferous tubules with active spermatogenesis, most Sertoli cells were negative for anti-p-STAT3 staining. Albeit rarely, a small patch of several p-STAT3-positive Sertoli cells was detected frequently in seminiferous epithelial cycle stages I-VI. Such p-STAT3-positive ratios in the convoluted seminiferous epithelia were significantly increased in germ cell-less testes than in the wild-type testes, but with considerably lower ratios than in the SV region. These findings imply that regionally distinct patterns of STAT3 phosphorylation in the Sertoli cells depend on either location or spermatogenic activity in normal healthy testes in vivo, highlighting a novel entry point to understanding STAT signaling in mammalian spermatogenesis.