Human Testis Research Articles

Mammalian testes utilize multiple modalities to moderate spermatogonial responsiveness to retinoic acid

What is knownThe foundation of mammalian spermatogenesis is provided by undifferentiated spermatogonia that proliferate before responding to retinoic acid (RA). RA converts undifferentiated into differentiating spermatogonia committed to entering meiosis. This RA‐regulated fate transition is essential for maintaining normal ratios of spermatogonia during steady‐state spermatogenesis in adult testes. Imbalances in spermatogonial populations often result in infertility – enhanced differentiation leads to eventual germline depletion, while impaired differentiation increases the likelihood of developing testicular cancer.Study ObjectiveDefine the extent cell autonomous and non‐autonomous mechanisms in adult mammalian spermatogonia regulate their response to RA.HypothesisOnly spermatogonia primed to differentiate will respond to RA and precociously progress through spermatogenesis.MethodologyAdult mice were treated in vivo with vehicle (DMSO), RA, or talarozole (RA catabolism inhibitor) and euthanized 12‐48 hours later. Testes were removed and various assays used to assess populations for responsiveness to RA and capacity to precociously differentiate and enter meiosis. Concurrently, a model of synchronized spermatogenesis was used to define the potential of sequential subsets of differentiating spermatogonia to respond to RA and precociously enter meiosis. In complementary ex vivo experiments, mouse testes and patient‐derived testicular biopsies were cultured with DMSO‐alone, RA, and/or talarozole for 6‐24 hours to evaluate RA responsiveness and changes in spermatogonia fate using immunostaining and qRT‐PCR.Main resultsExogenous RA elicited a rapid (12 hour) and significant increase in expression of the RA‐responsive gene ‘stimulated by retinoic acid 8’ (STRA8) in undifferentiated (ZBTB16+) spermatogonia. STRA8 expression decreased over the next 36 hours, such that numbers of STRA8+/ZBTB16+ spermatogonia were comparable in testes from vehicle‐ and RA‐treated mice. This transient increase in STRA8 affected spermatogonia at all stages of spermatogenesis. Exogenous RA also elicited STRA8 expression in differentiating (KIT+) spermatogonia in adults and synchronized mice. Despite this capacity for responding to exogenous RA, obvious precocious progression was not observed within the testis. Talarozole treatment elicited STRA8 expression in spermatogonia akin to RA treatments. Finally, qRT‐PCR showed adult mouse and human testes regulate responsiveness to RA similarly, based on mRNA expression profiles.ConclusionIn response to exogenous RA, undifferentiated spermatogonia transiently upregulate expression of RA‐responsive genes, but this did not result in precocious progression into meiosis.ImplicationsThe adult mammalian testis is a well‐buffered system in which exogenous RA has little effect on cell fate, thus preserving the normal timing and progression of spermatogenesis.

Single-cell analysis of human testis aging and correlation with elevated body mass index.

Aging men display reduced reproductive health; however, testis aging is poorly understood at the molecular and genomic levels. Here, we utilized single-cell RNA-seq to profile over 44,000 cells from both young and older men and examined age-related changes in germline development and in the testicular somatic cells. Age-related changes in spermatogonial stem cells appeared modest, whereas age-related dysregulation of spermatogenesis and somatic cells ranged from moderate to severe. Altered pathways included signaling and inflammation in multiple cell types, metabolic signaling in Sertoli cells, hedgehog signaling and testosterone production in Leydig cells, cell death and growth in testicular peritubular cells, and possible developmental regression in both Leydig and peritubular cells. Remarkably, the extent of dysregulation correlated with body mass index in older but not in younger men. Collectively, we reveal candidate molecular mechanisms underlying the complex testicular changes conferred by aging and their possible exacerbation by concurrent chronic conditions such as obesity.

Mouse-human species differences in early testicular development and its implications

The mouse has been used as a model of human organogenesis with the tacit assumption that morphogenetic and molecular mechanisms in mice are translatable to human organogenesis. While many morphogenetic and molecular mechanisms are shared in mice and humans, many anatomic, morphogenetic, and molecular differences have been noted. Two critical gaps in our knowledge prevent meaningful comparisons of mouse versus human testicular development: (a) human testicular development is profoundly under-represented in the literature, and (b) an absence of a detailed day-by-day ontogeny of mouse testicular development from E11.5 to E16.5 encompassing the ambisexual stage to seminiferous cord formation. To address these deficiencies, histologic and immunohistochemical studies were pursued in comparable stages of mouse and human testicular development with a particular emphasis on Leydig, Sertoli and myoid cells through review of the literature and new observations. For example, an androgen-receptor-positive testicular medulla is present in the developing human testis but not in the developing mouse testis. The human testicular medulla and associated mesonephros were historically described as the source of Sertoli cells in seminiferous cords. Consistent with this idea, the profoundly androgen receptor (AR)-positive human testicular medulla was shown to be a zone of mesenchymal to epithelial transition and a zone from which AR-positive cells appear to migrate into the human testicular cortex. While mouse Sertoli and Leydig cells have been proposed to arise from coelomic epithelium, Sertoli (SOX9) or Leydig (HSD3B1) cell markers are absent from the immediate coelomic zone of the developing human testis, perhaps because Leydig and Sertoli cell precursors are undifferentiated when they egress from the coelomic epithelium. The origin of mouse and human myoid cells remains unclear. This study provides a detailed comparison of the early stages of testicular development in human and mouse emphasizing differences in developmental processes.

Methamphetamine can induce alteration of histopathology and sex determination gene expression through the oxidative stress pathway in the testes of human post-mortem.

Methamphetamine is a recreational drug that can be taken ingestion orally, injected, smoked or snorted. Methamphetamine abuse may lead to male infertility. The purpose of this study was to evaluate the long-term effects of methamphetamine abuse on the sex reprogramming of human post-mortem testis. Testes were collected from the autopsies of methamphetamine users (n= 10) and healthy males (reference group) (n= 10). They were then taken for stereological studies and RNA extraction to evaluate the expressions of PCNA, DMRT1, SOX8, c-Kit, TNF-α, IL6 and FOXL2 genes. In addition, Reactive Oxygen Species (ROS) level and Glutathione Disulfide (GSH) were assessed. Autopsied testicular samples of methamphetamine revealed a significant reduction in stereological parameters and histopathological findings, suggesting methamphetamine as a practical approach to prevention strategies in reproductive medicine that can disrupt spermatogenesis. Moreover, the results indicated the expressions of the genes involved in testis function and male-to-female genetic reprogramming (PCNA, DMRT1, SOX8, c-Kit, TNF-α, IL6 and FOXL2) (16) as well as in increasing inflammation (TNF-α and IL-6). The results also showed a high level of ROS and a decrease in GSH activity. The results of SOX9 immunohistochemistry indicated a significant decrease in the expression of SOX9 as well as in the number of Sertoli cells in the methamphetamine group. Overall, the results suggested that methamphetamine abuse caused spermatogenesis disruption and genetic reprogramming, probably through oxidative stress and changes in the expression of sex-determining genes.

PA1 participates in the maintenance of blood\u2013testis barrier integrity via cooperation with JUN in the Sertoli cells of mice

BackgroundThe blood–testis barrier (BTB) is essential to the microenvironment of spermatogenesis, and Sertoli cells provide the cellular basis for BTB construction. Numerous nuclear transcription factors have been identified to be vital for the proper functioning of Sertoli cells. PA1 has been reported to play important roles during diverse biological processes, yet its potential function in male reproduction is still unknown.ResultsHere, we show that PA1 was highly expressed in human and mouse testis and predominantly localized in the nuclei of Sertoli cells. Sertoli cell-specific Pa1 knockout resulted in an azoospermia-like phenotype in mice. The knockout of this gene led to multiple defects in spermatogenesis, such as the disorganization of the cytoskeleton during basal and apical ectoplasmic specialization and the disruption of the BTB. Further transcriptomic analysis, together with Cut-Tag results of PA1 in Sertoli cells, revealed that PA1 could affect the expression of a subset of genes that are essential for the normal function of Sertoli cells, including those genes associated with actin organization and cellular junctions such as Connexin43 (Cx43). We further demonstrated that the expression of Cx43 depended on the interaction between JUN, one of the AP-1 complex transcription factors, and PA1.ConclusionOverall, our findings reveal that PA1 is essential for the maintenance of BTB integrity in Sertoli cells and regulates BTB construction-related gene expression via transcription factors. Thus, this newly discovered mechanism in Sertoli cells provides a potential diagnostic or even therapeutic target for some individuals with azoospermia.

Nanostructure stable hydrophilic hierarchical porous metal-organic frameworks for highly efficient enrichment of glycopeptides.

Protein glycosylation plays a vital role in many physiological activities in organisms. Due to the low abundance of glycopeptides and the interference of numerous non-glycopeptides in biological samples, selective enrichment of glycopeptides is of great significance for their successful identification. Metal organic frameworks (MOFs) materials are appropriate for glycopeptides enrichment by virtue of their large specific surface area and outstanding hydrophilic properties. However, the instability of hydrophilic MOFs in acidic solutions have severely limited their applications. In this work, a rational facile strategy was established to synthesize a stable hydrophilic hierarchical porous MOF (denoted as HP-MOF-Arg@mSiO2). This new material improved the selectivity and sensitivity of enrichment for glycopeptides via modification of arginine groups. More importantly, the mesoporous silica layer was introduced to enhance the stability of MOFs in aqueous solution and achieve the size exclusion effect of large-size proteins in complex samples. Overall, owing to the unique hierarchical porous and the hydrophilic modification, the synthesized HP-MOF-Arg@mSiO2 materials showed excellent hydrophilicity and hydrolytic stability, resulting in outstanding specific separation capacity in glycopeptides enrichment. A total of 521 and 342 glycopeptides were respectively captured from 2μL human serum digests and mouse testis tissue digests, revealing the potential of the materials in the study of glycoproteomics in complex biological samples.

Endogenous Effects of Leptin on Leydig Stem Cell Differentiation through Desert Hedgehog Signaling Pathway

ABSTRACT Introduction Although testosterone deficiency (TD) may be present in 1 out of 5 men 40 years or older, the factors responsible for TD remain largely unknown. Leydig stem cells (LSCs) differentiate into adult Leydig cells (ALC) and produce testosterone in the testes under the pulsatile control of luteinizing hormone (LH) from the pituitary gland. However, our recent studies have suggested that the testicular microenvironment (TME), which is comprised of Sertoli and peritubular myoid cells (PMC), plays an instrumental role in LSC differentiation and testosterone production under the regulation of the desert hedgehog signaling pathway (DHH). In the present study, we hypothesized that testicular TME releases paracrine factors that modulate LSC differentiation. Objective To further examine the TME its see if its release of paracrine factors modulates LSC differentiation. Methods A total of 13 men with testicular failure underwent testis biopsies for sperm retrieval. Using an IRB approved protocol, about 10mg of testicular tissue from each of these men were processed for Leydig stem cell isolation, culture and characterized. Cytokine antibody array was performed to identify the paracrine factors released by TME. The cells were treated with hedgehog signaling agonist and antagonist in the presence or absence of identified paracrine factors from the conditioned media. Two independent biopsies were treated with siRNA against LEPR (25pmol) for 48hrs. This was followed by evaluating the extent of knockdown on LEPR and B3HSD. Further, to evaluate the functional aspects (cell proliferation) modulated by Leptin-DHH signalling by first sorting the Sertoli cells, Peritubular myoid cells, Leydig stem cells and Adult Leydig cells using surface markers. These cells were then treated with Hedgehog agonist (SAG) and antagonist (Vismodigib), in the presence or absence of increasing doses of Leptin (0, 1, 10 ng/ml respectively) 48 hours post treatment, these cells were used for checking the impacts of Leptin-DHH treatments on cell proliferation by MTT assay. GraphPad Prism (GraphPad Software) was used for statistical analysis. All data were presented as the means ± SEM. The statistical significance between two groups was estimated by unpaired two-tailed t-test. Results We successfully isolated and cultured up to 5 × 106million LSC's / biopsy from all 13 human testis biopsies. These cells were characterized for the presence or absence of different cell types in testis such as adult Leydig cells, Leydig stem cells, Sertoli cells, peritublar myoid cells and germ cells. Results showed that, of the cells cultured, up to 70% of the cells were Leydig stem cells and 10% of them were Sertoli-cell in origin on day 14. IF and qPCR data showed as the majority of cell population was undifferentiated (PDGFR-α). Upon stimulation by LH, the expression of 3βHSD (mature Leydig cells) was increased and that of PDGFR-α was decreased. Results from siRNA against LEPR has shown the down-regulated LEPR and B3HSD expression levels. The results from cell proliferation showed that there is minimal to no impact of leptin treatment on upon DHH agonist (SAG) or antagonist (Vismodigib) treatment in either cell types therefore suggesting that Leptin is not involving in the proliferation mechanism. Furthermore, the results demonstrated that TME secretes leptin which induces LSC differentiation and increases T production. Leptin's effects on LSC differentiation and T production, however, are inversely concentration-dependent: positive at low doses and negative at higher doses. Mechanistically, leptin acts on LSCs upstream of DHH; leptin-DHH regulation functions unidirectionally insofar as DHH gain or loss of function has no effects on leptin levels. Conclusions Taken together, results from this study demonstrate the instrumental role of leptin as a paracrine factor secreted by TME on human LSC function and differentiation. Moreover, this study established the molecular events (DHH signaling) that underlie the leptin-modulated effects on LSCs. Further studies are ongoing to validate the implications of these Leptin in terms of its role in LSCs function, differentiation and survival Disclosure No

The Effect of COVID-19 Infection on Male Fertility: A Narrative Review

The emergence of a new coronavirus, officially referred to as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2 ), has challenged all healthcare workers and clinicians worldwide. The presence of the virus in biological fluids including the semen has raised some concerns about infertility treatment. There is evidence that SARS-CoV-2, which causes coronavirus disease 2019 (COVID-19), can damage the male reproductive system following the inflammatory process caused by the cytokine storm. However, the direct and long-term effects of SARS-CoV-2 on fertility and the reproductive capacity of the human testis are still open to controversy. The lasting presence of the virus, even after a complete recovery, can increase the risk of sexual transmission and adversely affect the male reproductive system, sexual function, and fertility. Therefore, there is a need for a careful assessment of reproductive organs and testicular function in male patients. This study aimed to evaluate the invasive effect of SARS-CoV-2 on the testis and male reproduction.

Regulation of STUB1 expression and its biological significance in mouse Sertoli cells

STIP1 Homology and U-Box Containing Protein 1 (STUB1), a ubiquitin E3 ligase initially involved in immune responses, has recently emerged as a pleiotropic regulator of different biological systems, including skeletal and male reproduction systems. On the latter, a homozygous mutation in the STUB1 gene has been identified in patients with hypogonadism. However, the pattern of expression and biological actions of STUB1 in testis remains so far unexplored. Herein, we report analyses on the testicular expression of STUB1 in human testes with impaired spermatogenesis and paracrine regulation of STUB1 expression in mouse testis development and the direct effects of ablation STUB1 on Sertoli cell (SC) functions. STUB1 was expressed abundantly in pachytene spermatocytes and SCs, and weakly in spermatogonia and differentiating spermatids in normal human testis. In contrast, Sertoli-specific expression of STUB1 was significantly decreased in the human testes with impaired spermatogenesis. Throughout postnatal development of mouse testis, however, STUB1 was expressed exclusively in the nuclei of the functionally mature SCs. The adjacent germ cell (GC)-derived IL-1α overtly regulated STUB1 expression through promoting the ETS domain transcription factor Elk-1 (ELK1)-mediated transactivation. Importantly, ablation of endogenous STUB1 caused lipid accumulation and senescence in GC co-incubated SCs. Together with previous reports on the stimulatory effects of IL-1α on cell senescence, our findings suggest that STUB1 may serve as an important negative feedback signaling to modulate the magnitude of GCs-derived IL-1α, which is normally maintained at low levels within testis.

Development of the human fetal testis: Morphology and expression of cellular differentiation markers

A comprehensive immunohistochemical ontogeny of the developing human fetal testis has remained incomplete in the literature to date. We collected human fetal testes from 8 to 21 weeks of fetal age, as well as postnatal human testes at minipuberty, pre-pubertal, and pubertal stages. Immunohistochemistry was performed with a comprehensive panel of antigens targeting gonadocytes, Sertoli cells, fetal Leydig cells, peritubular myoid cells, and other hormonal and developmental targets.Testicular cords, precursor structures to seminiferous tubules, developed from 8 to 14 weeks of fetal age, separating the testis into the interstitial and intracordal compartments. Fetal gonadocytes were localized within the testicular cords and evaluated for Testis-Specific Protein Y, Octamer-binding transcription factor 4, Sal-like protein 4, and placental alkaline phosphatase expression. Fetal Sertoli cells were also localized in the testicular cords and evaluated for SRY-box Transcription Factor 9, inhibin, and anti-Mullerian hormone expression. Fetal Leydig cells were present in the interstitium and stained for cytochrome p450c17 and calretinin, while interstitial peritubular myoid cells were examined using smooth muscle α-actin staining. Androgen receptor expression was localized close to the testicular medulla at 8 weeks and then around the testicular cords in the interstitium as they matured in structure.Postnatal staining showed that Testis-Specific Protein Y remained positive of male gonadocytes throughout adulthood. Anti-Mullerian hormone, SRY-box Transcription Factor 9, and Steroidogenic factor 1 are expressed by the postnatal Sertoli cells at all ages examined. Leydig cell markers cytochrome p450c17 and calretinin are expressed during mini-puberty and puberty, but not expressed during the pre-pubertal period. Smooth muscle α-actin and androgen receptor were not expressed during mini-puberty or pre-puberty, but again expressed during the pubertal period.The ontogenic map of the human fetal and postnatal testicular structure and expression patterns described here will serve as a reference for future investigations into normal and abnormal testicular development.

SARS-CoV-2 and Its Implications for the Human Reproductive System: A Review Article

Context: The SARS-CoV-2 virus causes dysfunction of vital organs in the body. Concerns about the destructive effect of SARS-CoV-2 on human reproductive tissues and fertility have increased. Evaluation of the possible mechanisms by which SARS-CoV-2 causes infertility is essential for effective prevention and treatment. This review aims to assess the studies that have been conducted on SARS-CoV-2 impacts on the human reproductive system. Evidence Acquisition: This review study investigated articles indexed in PubMed, Science-Direct, Scopus, and google scholar databases from 2019 to 2021. The Keywords SARS-CoV-2, COVID-19, human reproductive system, testis, and ovary were searched in the mentioned databases. Results: The present study assessed the expression of SARS-CoV-2-specific receptors, the presence of the virus in the human reproductive system, and the mechanisms by which this virus can affect human fertility. Conclusions: SARS-CoV-2, like other viruses, may indirectly influence the male reproductive system through cytokine storms, inflammation-causing oxidative stress, and its possible complications. The direct effects of SARS-CoV-2 on the male reproductive system are also reported. The testis may be a potential target for the SARS-CoV-2 virus. The impact of the SARS-CoV-2 virus on women's reproductive performance is unknown and requires further investigation.

GIPR gene expression in testis is mouse specific and can impact male mouse fertility.

Glucose-dependent insulinotropic polypeptide receptor (Gipr) gene expression has been reported in mouse spermatids and Gipr knockout male mice have previously been reported to have decreased in vitro fertilization, although the role of Gipr signaling in male mouse fertility is not well understood. The purposes of these studies were to determine the role of glucose-dependent insulinotropic polypeptide receptor in male fertility using Gipr knockout mice and anti-glucose-dependent insulinotropic polypeptide receptor antibody-treated wild-type mice and to determine if the expression of Gipr in mouse testes is similar in non-human and human primates. Adiponectin promoter-driven Gipr knockout male mice (GiprAdipo-/- ) were assessed for in vitro and in vivo fertility, sperm parameters, and testicular histology. CD1 male mice were administered an anti-glucose-dependent insulinotropic polypeptide receptor antibody (muGIPR-Ab) prior to and during mating for assessment of in vivo fertility and sperm parameters. Expression of Gipr/GIPR mRNA in the mouse, cynomolgus monkey, and human testes was assessed by in situ hybridization methods using species-specific probes. GiprAdipo-/- male mice are infertile in vitro and in vivo, despite normal testis morphology, sperm counts, and sperm motility. In contrast, administration of muGIPR-Ab to CD1 male mice did not impact fertility. While Gipr mRNA expression is detectable in the mouse testes, GIPR mRNA expression is not detectable in monkey or human testes. The infertility of GiprAdipo-/- male mice correlated with the lack of Gipr expression in the testis and/or adipocyte tissue. However, as administration of muGIPR-Ab did not impact the fertility of adult male mice, it is possible that the observations in genetically deficient male mice are related to Gipr deficiency during development. Our data support a role for Gipr expression in the mouse testis during the development of sperm fertilization potential, but based on gene expression data, a similar role for glucose-dependent insulinotropic polypeptide receptor in non-human primate or human male fertility is unlikely.

Mast Cells in the Mammalian Testis and Epididymis-Animal Models and Detection Methods.

Mast cells (MCs) are an evolutionary well-conserved type of cells, mediating and modulating allergic responses in innate immunity and tissue remodeling after chronic inflammation. Among other tissues, they inhabit both the testis and epididymis. In the testis, MCs usually appear in the interstitial compartment in humans, but not in other standard experimental models, like rats and mice. MCs seem to be responsible for testicular tissue fibrosis in different causes of infertility. Although experimental animal models follow the effect on MC activation or penetration to the interstitial tissue like in humans to some extent, there is an inconsistency in the available literature regarding experimental design, animal strain, and detection methods used. This comprehensive review offers an insight into the literature on MCs in mammalian testes and epididymides. We aimed to find the most suitable model for research on MC and offer recommendations for future experimental designs. When using in vivo animal models, tunica albuginea incorporation and standard histological assessment need to be included. Domesticated boar strains kept in modified controlled conditions exhibit the highest similarity to the MC distribution in the human testis. 3D testicular models are promising but need further fine-tuning to become a valid model for MC investigation.

Review of SARS-CoV-2 infects, replicates, elevates angiotensin II and activates immune cells in human testes

Review of SARS-CoV-2 infects, replicates, elevates angiotensin II and activates immune cells in human testes

Characterization of the pVHL Interactome in Human Testis Using High-Throughput Library Screening.

Simple SummaryThe von Hippel–Lindau (pVHL) tumor suppressor is a protein that regulates the normal cell adaptation to low oxygen concentrations. When its function is altered by inherited or acquired mutation pVHL becomes causative of a familiar predisposition to develop different types of cancers. Besides this role, pVHL is also thought to have other relevant cell functions, and studies in mice demonstrated that this protein is crucial for correct testis development and sperm maturation. By scanning the testis-specific library, we identified 55 novel proteins that interact with the human pVHL, with many of them directly participating in metabolic pathways frequently altered in cancer. Furthermore, our results suggest that pVHL may be also important for correct gonad function in men.Functional impairment of the von Hippel–Lindau tumor suppressor (pVHL) is causative of a familiar increased risk of developing cancer. As an E3 substrate recognition particle, pVHL marks the hypoxia inducible factor 1α (HIF-1α) for degradation in normoxic conditions, thus acting as a key regulator of both acute and chronic cell adaptation to hypoxia. The male mice model carrying VHL gene conditional knockout presents significant abnormalities in testis development paired with defects in spermatogenesis and infertility, indicating that pVHL exerts testis-specific roles. Here we aimed to explore whether pVHL could have a similar role in humans by performing a testis-tissue library screening complemented with in-depth bioinformatics analysis. We identified 55 novel pVHL binding proteins directly involved in spermatogenesis, cell differentiation and reproductive metabolism. In addition, computational investigation of these new interactors identified multiple pVHL-specific binding motifs and demonstrated that somatic mutations described in human cancers reside in these binding regions. Collectively, these findings suggest that, in addition to its role in cancer formation, pVHL may also be pivotal in normal gonadal development in humans.

Cell-Cell Interaction-Mediated Signaling in the Testis Induces Reproductive Dysfunction-Lesson from the Toxicant/Pharmaceutical Models.

Emerging evidence has shown that cell-cell interactions between testicular cells, in particular at the Sertoli cell-cell and Sertoli-germ cell interface, are crucial to support spermatogenesis. The unique ultrastructures that support cell-cell interactions in the testis are the basal ES (ectoplasmic specialization) and the apical ES. The basal ES is found between adjacent Sertoli cells near the basement membrane that also constitute the blood-testis barrier (BTB). The apical ES is restrictively expressed at the Sertoli-spermatid contact site in the apical (adluminal) compartment of the seminiferous epithelium. These ultrastructures are present in both rodent and human testes, but the majority of studies found in the literature were done in rodent testes. As such, our discussion herein, unless otherwise specified, is focused on studies in testes of adult rats. Studies have shown that the testicular cell-cell interactions crucial to support spermatogenesis are mediated through distinctive signaling proteins and pathways, most notably involving FAK, Akt1/2 and Cdc42 GTPase. Thus, manipulation of some of these signaling proteins, such as FAK, through the use of phosphomimetic mutants for overexpression in Sertoli cell epithelium in vitro or in the testis in vivo, making FAK either constitutively active or inactive, we can modify the outcome of spermatogenesis. For instance, using the toxicant-induced Sertoli cell or testis injury in rats as study models, we can either block or rescue toxicant-induced infertility through overexpression of p-FAK-Y397 or p-FAK-Y407 (and their mutants), including the use of specific activator(s) of the involved signaling proteins against pAkt1/2. These findings thus illustrate that a potential therapeutic approach can be developed to manage toxicant-induced male reproductive dysfunction. In this review, we critically evaluate these recent findings, highlighting the direction for future investigations by bringing the laboratory-based research through a translation path to clinical investigations.

Advances in research of TGF-Β1 in human testis

Transforming growth factor β1 (TGF-β1) is a polypeptide growth factor with various biological activities. Recent studies have shown that this growth factor and they receptors are expressed in human Leydig cells, Sertoli cells, spermatogonia, spermatocytes and sperm cells after birth, and are involved in the endocrine regulation of spermatogenesis. However, there is no report on the expression of TGF-β in human embryonic testis. TGF-β1 is a peptide growth factor widely distributed in germ cells at various levels in the testis, regulating the function of the testes and maintaining the stability of the testis environment by acting on various cells. This review summarizes the research progress of TGF-β1 in human testis.

More than a Gender Issue: Testis as a Distinctive HIV Reservoir and Its Implication for Viral Eradication.

Early establishment of HIV reservoir represents the main impediment to an HIV cure. Mainly composed of infected memory CD4 T-cells and macrophages, HIV reservoirs are found in several organs including lymph nodes, gut, and testes. In men, and as seen in brain and eyes, testes represent a distinctive organ characterized by an immune privilege, allowing the tolerance of spermatozoa which only develop after puberty, long after the establishment of systemic immunity. The immune privilege of testes relies on a strict testis-blood barrier, and a local immunosuppressive environment. Testes has been described as reservoir for several viruses including Ebola, Zika, and HIV. Indeed, HIV reservoirs were detected in tested viremic and virally suppressed donor taking antiretroviral therapy (ART). Herein, we discuss the distinctive environment found in human testes and describe a validated method allowing the characterization and quantification of HIV-infected CD4 T-cells in human testes. Using mechanical and enzymatic treatment, cells can be extracted from human testis samples. Characterization of those cells can be performed by flow cytometry and HIV reservoir quantification performed by nested qPCR after flow cytometry sorting.

Single-cell transcriptome analysis of Bisphenol A exposure reveals the key roles of the testicular microenvironment in male reproduction.

Testicular development during juvenile is crucial for subsequent male reproductive function. However, it remains poorly understood about the contribution of the testis microenvironment to human germ cell maturation. Therefore, we systematically analyzed scRNA-seq transcriptome and found the dramatic changes in cell-type composition in human testis during puberty. Then we constructed cell-cell communication networks between germ cells and somatic cells in the juvenile testis, which may be achieved via immune-related pathways. Our results showed that maturation-promoting factors are the switches of the Sertoli cells that drive sperm maturation. Furthermore, we found that Bisphenol A(BPA) enhanced the maturation and growth of germ cells through the Sertoli cell's secretory protein. Finally, our results indicate Bisphenol A would lead to the dysregulation of secreted protein expression in Sertoli cells during spermatogenesis, which in turn has direct cytotoxicity to Sertoli cells. Bisphenol A is one of the underlying causes of non-obstructive azoospermia (NOA). In summary, our results reveal the reproductive toxicity and molecular mechanism of Bisphenol A in Sertoli cells and male reproduction. Provide a reference for the toxicity of Bisphenol A to human reproduction.

Assessment of SARS-CoV-2 RNA shedding in semen of 36 males with symptomatic, asymptomatic, and convalescent infection during the first and second wave of COVID-19 pandemic in Italy.

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) receptor, angiotensin-converting enzyme 2 (ACE2), has been identified in the human testis, but the risk of transmission of SARS-CoV-2 through sexual intercourse still needs to be defined. The goal of our study was to determine if SARS-CoV-2 is detectable in the semen of patients suffering or recovering from coronavirus disease-19 (COVID-19), still testing positive at nasopharyngeal swabs but showing mild or no symptoms at the time of sampling. Detection of SARS-CoV-2 RNA in semen was performed by real-time reverse transcriptase-polymerase chain reaction (RT-PCR) and nested PCR targeting open reading frame (ORF) 1ab. Medical history of the enrolled patients was taken, including COVID-19-correlated symptoms, both at the time of diagnosis and at the time of interview. Results of real-time RT-PCR and nested PCR in semen showed no evidence of SARS-CoV-2 RNA in the 36 patients suffering or recovering from COVID-19 but still positive in a nasopharyngeal swab, from over 116 patients enrolled in the study. SARS-CoV-2 detection and persistence in semen would have an impact on both clinical practice and public health strategies, but our results would suggest that SARS-CoV-2 is not present in the semen of men recovering from COVID-19.