Blood-testis barrier and spermatogenesis: lessons from genetically-modified mice

DNA Aptamer Raised against Advanced Glycation End Products Improves Sperm Concentration, Motility, and Viability by Suppressing Receptors for Advanced Glycation End Product-Induced Oxidative Stress and Inflammation in the Testes of Diabetic Mice

Type 2 diabetes mellitus (T2DM) is a risk factor for male infertility, but the underlying molecular mechanisms remain unclear. Advanced glycation end products (AGEs) are pathogenic molecules for diabetic vascular complications. Here, we investigated the effects of the DNA aptamer raised against AGEs (AGE-Apt) on testicular and sperm abnormalities in a T2DM mouse model. KK-Ay (DM) and wild-type (non-DM) 4- and 7-week-old male mice were sacrificed to collect the testes and spermatozoa for immunofluorescence, RT-PCR, and histological analyses. DM and non-DM 7-week-old mice were subcutaneously infused with the AGE-Apt or control-aptamer for 6 weeks and were then sacrificed. Plasma glucose, testicular AGEs, and Rage gene expression in 4-week-old DM mice and plasma glucose, testicular AGEs, oxidative stress, and pro-inflammatory gene expressions in 7-week-old DM mice were higher than those in age-matched non-DM mice, the latter of which was associated with seminiferous tubular dilation. AGE-Apt did not affect glycemic parameters, but it inhibited seminiferous tubular dilation, reduced the number of testicular macrophages and apoptotic cells, and restored the decrease in sperm concentration, motility, and viability of 13-week-old DM mice. Our findings suggest that AGEs-Apt may improve sperm abnormality by suppressing AGE-RAGE-induced oxidative stress and inflammation in the testes of DM mice.

AZIN2 is associated with apoptosis of germ cells in undescended testis

Undescended testis (UDT), known as cryptorchidism (CRY), is a common congenital disorder in which one or both testicles do not descend normally into the scrotum. A unilateral UDT model was established by inducing UDT in mice through surgery. The results showed that the testis in the UDT model group was abnormal; the lumen of the seminiferous tubule was atrophic; apoptosis, necrosis and shedding were observed in many of the germ cells; the level of sex hormones was abnormal; and mature sperm was reduced. Subsequently, transcriptome sequencing was conducted on the testicular tissue of UDT model mice. Through analysis and verification of differential genes, AZIN2 was identified as playing a key role in the decline in male fertility caused by cryptorchidism. AZIN2 expression and spermine content was down-regulated in the testis of the UDT group. We then used a combination of hypoxanthine and xanthine to create a GC-1 cell damage model. In this model, AZIN2 expression and spermine content was down-regulated. When si-Azin2 transfected GC-1 cells, cell viability and proliferation were decreased. However, in the GC-1 cell damage model transfected with Azin2 over-expressed plasmid, AZIN2 expression and spermine content was up-regulated, reversing the cell damage caused by hypoxanthine and xanthine, and restoring the proliferation ability of GC-1 cells. These results indicate that in UDT, down-regulated AZIN2 expression is a factor in testicular damage. This discussion of the connection between AZIN2 and germ cells has important clinical significance as it provides an important reference for the diagnosis and treatment of cryptorchidism.

Loss of PBX1 function in Leydig cells causes testicular dysgenesis and male sterility

Leydig cells are essential components of testicular interstitial tissue and serve as a primary source of androgen in males. A functional deficiency in Leydig cells often causes severe reproductive disorders; however, the transcriptional programs underlying the fate decisions and steroidogenesis of these cells have not been fully defined. In this study, we report that the homeodomain transcription factor PBX1 is a master regulator of Leydig cell differentiation and testosterone production in mice. PBX1 was highly expressed in Leydig cells and peritubular myoid cells in the adult testis. Conditional deletion of Pbx1 in Leydig cells caused spermatogenic defects and complete sterility. Histological examinations revealed that Pbx1 deletion impaired testicular structure and led to disorganization of the seminiferous tubules. Single-cell RNA-seq analysis revealed that loss of Pbx1 function affected the fate decisions of progenitor Leydig cells and altered the transcription of genes associated with testosterone synthesis in the adult testis. Pbx1 directly regulates the transcription of genes that play important roles in steroidogenesis (Prlr, Nr2f2 and Nedd4). Further analysis demonstrated that deletion of Pbx1 leads to a significant decrease in testosterone levels, accompanied by increases in pregnenolone, androstenedione and luteinizing hormone. Collectively, our data revealed that PBX1 is indispensable for maintaining Leydig cell function. These findings provide insights into testicular dysgenesis and the regulation of hormone secretion in Leydig cells.

Forkhead-associated phosphopeptide binding domain 1 (FHAD1) deficiency impaired murine sperm motility

Background

Genetic knockout-based studies conducted in mice provide a powerful means of assessing the significance of a gene for fertility. Forkhead-associated phosphopeptide binding domain 1 (FHAD1) contains a conserved FHA domain, that is present in many proteins with phospho-threonine reader activity. How FHAD1 functions in male fertility, however, remains uncertain.

Methods

Fhad1-/- mice were generated by CRISPR/Cas9-mediated knockout, after which qPCR was used to evaluate changes in gene expression, with subsequent analyses of spermatogenesis and fertility. The testis phenotypes were also examined using immunofluorescence and histological staining, while sperm concentrations and motility were quantified via computer-aided sperm analysis. Cellular apoptosis was assessed using a TUNEL staining assay.

Results

The Fhad1-/-mice did not exhibit any abnormal changes in fertility or testicular morphology compared to wild-type littermates. Histological analyses confirmed that the testicular morphology of both Fhad1-/-and Fhad1+/+ mice was normal, with both exhibiting intact seminiferous tubules. Relative to Fhad1+/+ mice, however, Fhad1-/-did exhibit reductions in the total and progressive motility of epididymal sperm. Analyses of meiotic division in Fhad1-/-mice also revealed higher levels of apoptotic death during the first wave of spermatogenesis.

Discussion

The findings suggest that FHAD1 is involved in both meiosis and the modulation of sperm motility.

Genotoxicity of bisphenol AF in rats: Detrimental to male reproductive system and probable stronger micronucleus induction potency than BPA

Bisphenol AF (BPAF), as one of structural analogs of BPA, has been increasingly used in recent years. However, limited studies have suggested its adverse effects similar to or higher than BPA. In order to explore the general toxicity and genotoxicity of subacute exposure to BPAF, the novel 28-day multi-endpoint (Pig-a assay + micronucleus [MN] test + comet assay) genotoxicity evaluation platform was applied. Male rats were randomly distributed into seven main experimental groups and four satellite groups. The main experimental groups included BPAF-treated groups (0.5, 5, and 50 μg/kg·bw/d), BPA group (10 μg/kg·bw/d), two solvent control groups (PBS and 0.1% ethanol/99.9% oil), and one positive control group (N-ethyl-N-nitrosourea, 40 mg/kg bw). The satellite groups included BPAF high-dose recovery group (BPAF-HR), oil recovery group (oil-R), ENU recovery group (ENU-R), and PBS recovery group (PBS-R). All groups received the agents orally via gavage for 28 consecutive days, and satellite groups were given a recovery period of 35 days. Among all histopathologically examined organs, testis and epididymis damage was noticed, which was further manifested as blood-testis barrier (BTB) junction protein (Connexin 43 and Occludin) destruction. BPAF can induce micronucleus production and DNA damage, but the genotoxic injury can be repaired after the recovery period. The expression of DNA repair gene OGG1 was downregulated by BPAF. To summarize, under the design of this experiment, male reproductive toxicity of BPAF was noticed, which is similar to that of BPA, but its ability to induce micronucleus production may be stronger than that of BPA.

Possible mechanisms involved in the protective effect of lutein against cyclosporine-induced testicular damage in rats

Oxidative stress and aberrant inflammatory response have important implications in cyclosporin-induced reproductive functions. Previous studies have shown that agents with antioxidant and anti-inflammatory activities might be beneficial in reversing cyclosporin-induced reproductive impairment. Lutein is a naturally occurring compound with antioxidant and anti-inflammatory properties. However, the effect of lutein against cyclosporin-induced reproductive impairment remains in complete. Hence, we investigated the protective effect of lutein, specifically focusing on the role of nuclear factor erythroid 2 related factor-2 (Nrf2)/heme-oxygenase-1 (HO-1)/connexin-43 (Cx-43) upregulation system against cyclosporine-induced reproductive impairment. Six male Wistar rats were allotted into 5 groups and given daily gavage of cyclosporine (40 mg/kg) and/or lutein (30 mg/kg) for four (4) weeks or in combination, respectively. The testicular antioxidant scaffolds: superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH), add to sulfhydryl (T-SH), non-protein sulfhydryl (NP-SH), glutathione reductase (GR), glutathione-S -transferase (GST), glutathione peroxidase (GSH-Px), thiobarbituric acid reactive substances (TBARS), myeloperoxidase (MPO), testicular proinflammatory cytokines, apoptotic related protein, nucleic acids, sialic acid, testicular proton pump ATPase, stress responsive protein, BTB-related protein and total protein levels in the testes were assayed thereafter. Cyclosporin significantly increased NOX-1, TNF-α, IL-1β, MPO, caspase-3 and -9 levels, which were reversed by lutein. Lutein reversed cyclosporin-induced decreases in Nrf2, HO-1, BCL-2, cytochrome C, with corresponding increase in CAT, SOD, GSH, T-SH, NP-SH, GST, GR, GSH-Px, and Cx-43 levels compared to cyclosporin groups. Lutein also abates cyclosporin-induced alterations Na + -K + -ATPase activities. Our findings showed that lutein's protective effect against cyclosporin-induced reproductive impairment might be associated with mechanisms linked to its antioxidant, anti-apoptotic, and anti-inflammatory properties, notably through up-regulation of Nrf2/HO-1/Cx-43 signaling and down-regulation of NOX-1 signaling.

Molybdenum and cadmium cause blood-testis barrier dysfunction through ROS-mediated NLRP3 inflammasome activation in sheep

In this study, 24 healthy male sheep were divided into four groups: the control group, Mo group (45 mg Mo·kg-1·BW), Cd group (1 mg Cd·kg-1·BW), and Mo + Cd group (45 mg Mo·kg-1·BW + 1 mg Cd·kg-1·BW). The experiment was last for 50 d. The results showed that Mo and Cd co-exposure induced histopathological changes and ultrastructural damage, decreased the mRNA and protein expression levels of BTB (blood-testis barrier)-related factors (CX-43, ZO-1, OCLN) (P < 0.05) and the T-SOD and CAT activity (P < 0.05), increased the MDA content (P < 0.05) and the proinflammatory factors levels (P < 0.05) in sheep testes. Moreover, the results showed that a sharp decline in BTB-related factors and antioxidase activity, and a significant increase in reactive oxygen species (ROS) levels (P < 0.05) and the expression levels of NLRP3 inflammasome-related factors (P < 0.05) in primary Sertoli cells (SCs) under Mo and Cd co-exposure. However, treatment with a ROS scavenger or NLRP3 inflammasome inhibitors could relieve BTB damage and oxidative injury, reduce the production of ROS (P < 0.05) and decrease the level of inflammatory factors (P < 0.05). Overall, these results indicated that Mo and Cd co-exposure reduced BTB-related protein levels and promoted ROS production and inflammatory reactions by activating the ROS/NLRP3 inflammasome pathway in sheep testes, which eventually induced reproductive toxicity.

Sertoli cell-derived extracellular vesicles traverse the blood-testis barrier and deliver miR-24-3p inhibitor into germ cells improving sperm mobility

Asthenozoospermia, characterized by poor sperm motility, is a common cause of male infertility. Improving energy metabolism and alleviating oxidative stress through drug regimens are potential therapeutic strategies. In this study, we observed upregulated miR-24-3p levels in asthenozoospermia spermatozoa, contributing to energy metabolism disorder and oxidative stress by reducing GSK3β expression. Thus, reducing miR-24-3p levels using drugs is expected to improve sperm motility. The blood-testis barrier (BTB) protects the testis from xenobiotics and drugs. In this study, we found that Sertoli cell-derived small extracellular vesicles (SC-sEV) can traverse the BTB and enter germ cells. We successfully loaded miR-24-3p inhibitor into SC-sEV, creating the nano-drug SC-sEV@miR-24-3p inhibitor, which effectively delivers miR-24-3p inhibitor into germ cells. In a gossypol-induced mouse asthenozoospermia model, administration of SC-sEV@miR-24-3p inhibitor significantly improved sperm motility, in vitro fertilization success, and blastocyst formation rates. As anticipated, it also improved the litter size of asthenozoospermia mice. These results suggest that SC-sEV@miR-24-3p inhibitor holds promise as a potential clinical treatment for asthenospermia.

The Regulatory Effects of JAK2/STAT3 on Spermatogenesis and the Redox Keap1/Nrf2 Axis in an Animal Model of Testicular Ischemia Reperfusion Injury

The male reproductive system requires the pleiotropic activity of JAK/STAT to maintain its function, especially spermatogenesis. The study aims to investigate the effect of JAK2 signaling on the expression of the Keap1/Nrf2 axis, spermatogenesis, and the Sertoli cells (Sc) junctions in an animal model of testicular ischemia reperfusion injury (tIRI). Testes subjected to tIRI exhibited increased JAK2/STAT3 activity associated with spermatogenic arrest and reduced expression of the Sc junctions. In addition, there was an increased protein expression of Keap1 and decreased Nrf2., which was coupled with the downregulation of gene expression of antioxidant enzymes. Reduced SOD and CAT activities were accompanied by increased lipid peroxidation and protein carbonylation during tIRI. Increased caspase 9 activity and Bax/Bcl2 ratio indicated initiation of apoptosis. Inhibition of JAK2 activity by AG490 maintained the integrity of spermatogenesis and SC junctions, normalized the expression of the Keap1/Nrf2 axis and its downstream antioxidant enzymes, and prevented germ cell apoptosis. The results further emphasized the regulatory role of JAK2/STAT3 on spermatogenesis, Keap1/Nrf2 signaling, and maintenance of the testicular redox balance to combat testicular dysfunction and male infertility.

Protective role of autophagy in triptolide-induced apoptosis of TM3 Leydig cells

Background and Objectives

Triptolide (TP) is known to impair testicular development and spermatogenesis in mammals, but the mechanism of the side effects still needs to be investigated. The aim of the research is to confirm whether TP can cause autophagy in TM3 Leydig cells and the potential molecular pathway in vitro.

Methods

TM3 Leydig cells are used to investigate the molecular pathway through Western blot, detection of apoptosis, transmission electron microscopy for autophagosomes and so on.

Results

The data show that TP treatment resulted in the decreasing of the viability of TM3 cells due to the increased apoptosis. Treated with TP, the formation of autophagosomes, the decrease in P62, and the increase in the conversion of LC3-I to LC3-II suggested the induction of autophagy. The induction of autophagy has accompanied the activation of the mTOR/P70S6K signal pathway. The viability of the TM3 cells was further inhibited when they were co-treated with autophagy inhibitor, chloroquine (CQ).

Conclusion

All these data suggest that autophagy plays a very important role in antagonizing TM3 cell apoptosis during the TP exposure.

Study of spermatogenic and Sertoli cells in the Hu sheep testes at different developmental stages

Spermatogenesis is a highly organized process by which undifferentiated spermatogonia self-renew and differentiate into spermatocytes and spermatids. The entire developmental process from spermatogonia to sperm occurs within the seminiferous tubules. Spermatogenesis is supported by the close interaction of germ cells with Sertoli cells. In this study, testicular tissues were collected from Hu sheep at 8 timepoints after birth: 0, 30, 90, 180, 270, 360, 540, and 720 days. Immunofluorescence staining and histological analysis were used to explore the development of male germ cells and Sertoli cells in the Hu sheep testes at these timepoints. The changes in seminiferous tubule diameter and male germ cells in the Hu sheep testes at these different developmental stages were analyzed. Then, specific molecular markers were used to study the proliferation and differentiation of spermatogonia, the timepoint of spermatocyte appearance, and the maturation and proliferation of Sertoli cells in the seminiferous tubules. Finally, the formation of the blood-testes barrier was studied using antibodies against the main components of the blood-testes barrier, β-catenin, and ZO-1. These findings not only increased the understanding of the development of the Hu sheep testes, but also laid a solid theoretical foundation for Hu sheep breeding.

What do we know about blood-testis barrier? current understanding of its structure and physiology

Blood-testis barrier (BTB) creates a particular compartment in the seminiferous epithelium. Contacting Sertoli cell-Sertoli cell plasma membranes possess specialized junction proteins which present a complex dynamic of formation and dismantling. Thus, these specialized structures facilitate germ cell movement across the BTB. Junctions are constantly rearranged during spermatogenesis while the BTB preserves its barrier function. Imaging methods are essential to studying the dynamic of this sophisticated structure in order to understand its functional morphology. Isolated Sertoli cell cultures cannot represent the multiple interactions of the seminiferous epithelium and in situ studies became a fundamental approach to analyze BTB dynamics. In this review, we discuss the contributions of high-resolution microscopy studies to enlarge the body of morphofunctional data to understand the biology of the BTB as a dynamic structure. The first morphological evidence of the BTB was based on a fine structure of the junctions, which was resolved with Transmission Electron Microscopy. The use of conventional Fluorescent Light Microscopy to examine labelled molecules emerged as a fundamental technique for elucidating the precise protein localization at the BTB. Then laser-scanning confocal microscopy allowed the study of three-dimensional structures and complexes at the seminiferous epithelium. Several junction proteins, like the transmembrane, scaffold and signaling proteins, were identified in the testis using traditional animal models. BTB morphology was analyzed in different physiological conditions as the spermatocyte movement during meiosis, testis development, and seasonal spermatogenesis, but also structural elements, proteins, and BTB permeability were studied. Under pathological, pharmacological, or pollutant/toxic conditions, there are significant studies that provide high-resolution images which help to understand the dynamic of the BTB. Notwithstanding the advances, further research using new technologies is required to gain information on the BTB. Super-resolution light microscopy is needed to provide new research with high-quality images of targeted molecules at a nanometer-scale resolution. Finally, we highlight research areas that warrant future studies, pinpointing new microscopy approaches and helping to improve our ability to understand this barrier complexity.

Es-β-CATENIN affects the hemolymph-testes barrier in Eriocheir sinensis by disrupting cell junctions and cytoskeleton

β-CATENIN is an evolutionarily conserved multifunctional molecule that maintains cell adhesion as a cell junction protein to safeguard the integrity of the mammalian blood-testes barrier, and also regulates cell proliferation and apoptosis as a key signaling molecule in the WNT/β-CATENIN signaling pathway. In the crustacean Eriocheir sinensis, Es-β-CATENIN has been shown to be involved in spermatogenesis, but the testes of E. sinensis have large and well-defined structural differences from those of mammals, and the impact of Es-β-CATENIN in them is still unknown. In the present study, we found that Es-β-CATENIN, Es-α-CATENIN and Es-ZO-1 interact differently in the testes of the crab compared to mammals. In addition, defective Es-β-CATENIN resulted in increased Es-α-CATENIN protein expression levels, distorted and deformed F-ACTIN, and disturbed localization of Es-α-CATENIN and Es-ZO-1, leading to loss of hemolymph-testes barrier integrity and impaired sperm release. In addition to this, we also performed the first molecular cloning and bioinformatics analysis of Es-AXIN in the WNT/β-CATENIN pathway to exclude the effect of the WNT/β-CATENIN pathway on the cytoskeleton. In conclusion, Es-β-CATENIN participates in maintaining the hemolymph-testes barrier in the spermatogenesis of E. sinensis.

Putative adverse outcome pathways of the male reproductive toxicity derived from toxicological studies of perfluoroalkyl acids

Adverse outcome pathway (AOP) as a conceptual framework is a powerful tool in the field of toxicology to connect seemingly discrete events at different levels of biological organizations into an organized pathway from molecular interactions to whole organism toxicity. Based on numerous toxicological studies, eight AOPs for reproductive toxicity have been endorsed by the Organization for Economic Co-operation and Development (OECD) Task Force on Hazard Assessment. We have conducted a literature survey on the mechanistic studies on male reproductive toxicity of perfluoroalkyl acids (PFAAs), a class of global environmental contaminants with high persistence, bioaccumulation and toxicity. Using the AOP development strategy, five new AOPs for male reproductive toxicity were proposed here, namely (1) changes in membrane permeability leading to reduced sperm motility, (2) disruption of mitochondrial function leading to sperm apoptosis, (3) decreased gonadotropin-releasing hormone (GnRH) expression in hypothalamus leading to reduced testosterone production in male rats, (4) activation of the p38 signaling pathway leading to disruption of BTB in mice, (5) inhibition of p-FAK-Tyr407 activity leading to the destruction of BTB. The molecular initiating events in the proposed AOPs are different from those in the endorsed AOPs, which are either receptor activation or enzyme inhibition. Although some of the AOPs are still incomplete, they can serve as a building block upon which full AOPs can be developed and applied to not only PFAAs but also other chemical toxicants with male reproductive toxicity.

NECL2 regulates blood-testis barrier dynamics in mouse testes

The adhesion protein nectin-like molecule 2 (NECL2) is involved in spermatogenesis and participates in the connections between Sertoli cells and germ cells. Necl2 deficiency leads to infertility in male mice. We found that NECL2 is relatively highly expressed on the cell membranes of preleptotene spermatocytes. It is known that preleptotene spermatocytes pass through the blood-testis barrier (BTB) from the base of the seminiferous tubules to the lumen to complete meiosis. We hypothesized that the NECL2 protein on the surfaces of preleptotene spermatocytes has an effect on the BTB when crossing the barrier. Our results showed that Necl2 deficiency caused the levels of proteins in the BTB to be abnormal, such as those of Claudin 3, claudin 11, and Connexin43. NECL2 interacted and colocalized with adhesion proteins forming the BTB, such as Connexin43, Occludin, and N-cadherin. NECL2 regulated BTB dynamics when preleptotene spermatocytes passed through the barrier, and Necl2 deficiency caused BTB damage. Necl2 deletion significantly affected the testicular transcriptome, especially the expression of spermatogenesis-related genes. These results suggest that before meiosis and spermatid development occur, BTB dynamics regulated by NECL2 are necessary for spermatogenesis.

Polystyrene nanoplastics promote CHIP-mediated degradation of tight junction proteins by activating IRE1α/XBP1s pathway in mouse Sertoli cells

Microplastics (MPs) and nanoplastics (NPs) widely exist in human living environment and enter the body through water, food chain and breathing. Several studies have shown that MPs or NPs disrupt the blood-testis barrier in rodents. However, the molecular mechanism by which MPs and NPs damage the blood-testis barrier remains unclear. In the present study, our aim was to investigate the molecular mechanism of the destruction of blood-testis barrier induced by polystyrene (PS)-NPs. Mice were treated with 50 μg/kg·day PS-NPs by tail vein injection once daily for two consecutive days. The results showed that PS-NPs exposure significantly decreased the levels of tight junction (TJ) proteins ZO-2, occludin and claudin-11 in testis of mice. In vitro, we used TM4 Sertoli cells to explore the underlying mechanism of the decrease in TJ proteins induced by PS-NPs. We found that PS-NPs activated IRE1α and induced its downstream XBP1 splicing, which in turn elevated the expression of the E3 ubiquitin ligase CHIP, then CHIP triggers proteasomal degradation of ZO-2, occludin, and claudin-11 proteins. Our findings suggest that IRE1α/XBP1s/CHIP pathway is a pivotal mechanism of TJ proteins degradation induced by PS-NPs in mouse Sertoli cells. In conclusion, our results reveal that the degradation of TJ proteins is one of the mechanisms of blood-testis barrier destruction caused by acute exposure to PS-NPs.

Exploring the pharmacological mechanism of Shengjing capsule on male infertility by a network pharmacology approach

Background

Shengjing capsule (SJC) is a traditional Chinese medicine (TCM) and has gained widespread clinical application for the treatment of male infertility (MI). However, the pharmacological mechanism of SJC against MI remains vague to date.

Method

The active ingredients of SJC and their targets were identified from the database, and MI-related genes were retrieved from several databases. Protein–protein interaction (PPI) data were obtained to construct the PPI networks. The candidate targets of SJC against MI were identified through topological analysis of the PPI network. Functional enrichment analysis of candidate targets was performed, and the key target genes were identified from the gene-pathway network.

Results

We identified 154 active ingredients and 314 human targets of SJC, as well as 564 MI-related genes. Eight pharmacological network diagrams illustrating the interactions among herbs, active ingredients, targets, and pathways, were constructed. The four dominating network maps included a compound-target network of SJC, a compound-anti-MI targets network, a candidate targets PPI network, a pathway-gene network, and a drug-key compounds-hub targets-pathways network. Systematic analysis indicated that the targets of SJC in the treatment of MI mainly involved RPS6, MAPK1, MAPK3, MDM2, and DDX5. Pathway enrichment analysis showed that SJC had the potential to impact multiple biological pathways, such as cancer-related pathways, viral/bacterial infection-related pathways, and signal transduction-related pathways.

Conclusion

Our results preliminarily revealed the pharmacological basis and molecular mechanism SJC in treating MI, but further experimental research is required to verify these findings.

Quercetin Abates Aluminum Trioxide Nanoparticles and Lead Acetate Induced Altered Sperm Quality, Testicular Oxidative Damage, and Sexual Hormones Disruption in Male Rats

This study examined the effects of exposure to lead acetate (PbAc) and/or aluminum trioxide nanoparticles (Al₂O₃NPs) on testicular function. Additionally, the probable reproprotective effects of quercetin (QTN) against Al₂O₃NPs and PbAc co-exposure in male Sprague Dawely rats were assessed. Al₂O₃NPs (100 mg/kg b.wt.), PbAc (50 mg/kg b.wt.), and QTN (20 mg/kg b.wt.) were orally administered for 60 days. Then, spermiogram, histopathological examinations of the testis and accessory glands, and immunohistochemical detection of androgen receptors (AR) and tumor necrotic factor alpha (TNF-α) were achieved. Moreover, serum levels of male sex hormones and testicular levels of antioxidant indices were estimated. The results showed that Al₂O₃NP_s and/or PbAc caused significant sperm abnormalities, testicular oxidative stress, and histopathological changes. Furthermore, serum testosterone, LH, and FSH levels significantly decreased, while estradiol levels significantly increased. The Al₂O₃NPs and/or PbAc co-exposed group had more obvious disturbances. Furthermore, QTN co-administration significantly reversed the Al₂O₃NPs and PbAc-induced testicular histopathological alterations, reduced antioxidant defenses, and altered AR and TNF-α immune expression in testicular tissues. Conclusively, Al₂O₃NPs and/or PbAc evoked testicular dysfunction by inducing oxidative injury and inflammation. However, QTN oral dosing effectively mitigated the negative effects of Al₂O₃NPs and PbAc by suppressing oxidative stress and inflammation and improving the antioxidant defense system.

Melatonin alleviates the heat stress-induced impairment of Sertoli cells by reprogramming glucose metabolism

Sertoli cells (SCs) provide structural and nutritional support for developing germ cells. Normal glucose metabolism of SCs is necessary for spermatogenesis. Melatonin could alleviate the effects of heat stress on spermatogenesis. However, the influences of heat stress on glucose metabolism in SCs remain unclear, and the potential protective mechanisms of melatonin on SCs need more exploration. In this study, boar SCs were treated at 43°C for 30 min, and different concentrations of melatonin were added to protect SCs from heat stress-induced impairment. These results showed that heat stress-induced oxidative stress caused cell apoptosis, inhibited the pentose phosphate pathway, and decreased the ATP content. Furthermore, heat stress increased the expressions of glucose intake- and glycolytic-related enzymes, which enhanced the glycolysis activity to compensate for the energy deficit. Melatonin relieved heat stress-induced oxidative stress and apoptosis by activating the Kelch-like ECH-associated protein 1 (KEAP1)/NF-E2-related factor 2 signaling pathway to increase the capacity of antioxidants. In addition, melatonin enhanced heat-shock protein 90 (HSP90) expression through melatonin receptor 1B (MTNR1B), thereby stabilizing hypoxia-inducible factor-1α (HIF-1α). Activation of the HIF-1α signaling pathway enhanced glycolysis, promoted the pentose phosphate pathway, and increased cell viability. Our results suggest that melatonin reprograms glucose metabolism in SCs through the MTNR1B-HSP90-HIF-1α axis and provides a theoretical basis for preventing heat stress injury.

Do follicle-stimulating hormone receptor polymorphisms in infertile men influence intracytoplasmic sperm injection outcomes? A prospective cohort study

The follicle-stimulating hormone (FSH) and its receptor regulate the quantity and quality of spermatozoa production. Several studies have analyzed the effect of single nucleotide polymorphisms (SNPs) in exon 10 of the FSH receptor (FSHR) on basic semen parameters without yet reaching a firm consensus. The aim of this study was to evaluate the effect of p.Thr307Ala and p.Asn680Ser polymorphisms in exon 10 of the FSHR gene, in infertile men, on intracytoplasmic sperm injection (ICSI) outcomes. This study was conducted between March 2019 and February 2020 on infertile couples undergoing ICSI at Al Hadi Laboratory and Medical Center, Lebanon. Couples with severe infertility factors that may impair gametogenesis/embryogenesis (e.g. advanced maternal age, premature ovarian failure, underwent gonadotoxic treatments, etc.) were excluded from the study. Semen and blood samples were collected from infertile men on the day of oocyte collection. Infertile men (n = 173) were screened for FSHR variants using polymerase chain reaction-restriction fragment length polymorphism. Moreover, fertilization rates, embryo quality, and pregnancy outcomes were evaluated. Higher sperm concentrations were found in the p.Thr307Ala group than the p.Thr307Thr (P < 0.01) and p.Ala307Ala (P < 0.05) groups. Furthermore, fertilization rate was significantly lower in the p.Ala307Ala genotype than in the p.Thr307Thr genotype (P < 0.05). We showed that FSHR variants in infertile men undergoing ICSI could affect sperm concentration, motility, and fertilization rates. Therefore, it will be important to confirm these results in further studies using a larger sample size.

Bibliometric and visual analysis of blood-testis barrier research

Background: Extensive research on the blood-testis barrier has been undertaken in recent years. However, no systematic bibliometric study has been conducted on this subject. Our research aimed to identify the hotspots and frontiers of blood-testis barrier research and to serve as a guide for future scientific research and decision-making in the field.

Methods: Studies on the blood-testis barrier were found in the Web of Science Core Collection. VOSviewer, CiteSpace, and Microsoft Excel were used to conduct the bibliometric and visual analyses.

Results: We found 942 blood-testis barrier studies published in English between 1992 and 2022. The number of annual publications and citations increased significantly between 2011 and 2022, notably in the United States. China and the United States, the US Population Council, Endocrinology, and Cheng C. Yan were the most productive countries, institution, journal, and author, respectively. The study keywords indicated that blood-testis barrier research involves a variety of compositional features (tight junctions, cytoskeleton, adherens junctions), cell types (Sertoli cells, germ cells, Leydig cells, stem cells), reproductive toxicity (cadmium, nanoparticles, bisphenol-a), and relevant mechanisms (spermatogenesis, apoptosis, oxidative stress, dynamics, inflammation, immune privilege).

Conclusion: The composition and molecular processes of the blood-testis barrier as well as the blood-testis barrier in male infertility patients are the primary research hotspots in this field. In addition, future research will likely focus on treatment and the development of novel medications that target signal pathways in oxidative stress and apoptosis to preserve the blood-testis barrier. Further studies must extend to clinical diagnosis and therapy.

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.

The Role of ZIP9 and Androgen Receptor in the Establishment of Tight Junctions between Adult Rat Sertoli Cells

The blood-testis barrier (BTB) is formed from tight junctions (TJs) between Sertoli cells. This dynamic structure, which establishes an immune-privileged environment protecting haploid germ cells formed in puberty from cells of the innate immune system, protects male fertility. Testosterone produced in Leydig cells is one of the main regulators of TJ protein expression and BTB dynamics. Nevertheless, although it has been assumed that testosterone effects on TJs and BTB are mediated through the classical androgen receptor (AR), newer results call the importance of this receptor into question. ZIP9, a recently identified androgen receptor of plasma membranes, mediates testosterone effects that promote the expression of TJ proteins and TJ formation in a rat Sertoli cell line that lacks the classical AR. Although these findings suggest that ZIP9 mediates these testosterone effects, participation of the classical AR in these events cannot be excluded. Here we used immortalized adult rat Sertoli cells that express both ZIP9 and AR and addressed the involvement of these receptors in the stimulation of TJ protein expression and TJ formation in response to testosterone and to the androgenic peptide IAPG that acts via ZIP9. We find that both testosterone and IAPG trigger the so-called non-classical signaling pathway of testosterone and stimulate the expression of TJ-associated proteins and TJ formation. Silencing classical AR expression had no effect on the responses, whereas silencing of ZIP9 expression completely blocked them. Our results demonstrate that ZIP9 is the sole androgen receptor involved in the regulation of TJ protein expression and TJ formation at the BTB.

Testis-specific fascin component FSCN3 is dispensable for mouse spermatogenesis and fertility

BACKGROUND

Fascins belong to a family of actin-bundling proteins that are involved in a wide range of biological functions. FSCN3, a newly identified testis-specific actin-bundling protein, is specifically expressed in elongated spermatids. However, its in vivo function in mouse spermiogenesis remains unknown.

METHODS AND RESULTS

We generated Fscn3 knockout mice through CRISPR/Cas9 gene-editing technology. Fscn3^-/- mice displayed normal testis morphology and testis to bodyweight ratio, and sperm concentrations did not differ significantly between Fscn3^+/+ and Fscn3^-/- mice. Fertility assays consistently revealed that Fscn3^-/- mice are completely fertile and their reproductive status does not differ from that of wild-type. Moreover, hematoxylin and eosin staining of the testis sections of Fscn3^-/- mice detected various germ cells, ranging from spermatogonia to mature spermatozoa. Furthermore, the swimming velocity of the sperm of Fscn3^-/- mice was comparable to that of their wild-type littermates. Both Fscn3^+/+ and Fscn3^-/-mice had normal sperm morphology, indicating that the disruption of Fscn3 does not affect sperm morphology. The analysis of meiotic prophase I progression demonstrated normal prophase-I phases (leptonema to diplonema) in both Fscn3^+/+ and Fscn3^-/- mice, suggesting that Fscn3 is not essential for meiosis I.

CONCLUSION

Our study provides the first evidence that FSCN3 is a testis-specific actin-bundling protein that is not required for mouse spermatogenesis. Our results will help reproductive biologists focus their efforts on genes that are crucial for fertility and avoid research duplication.

Tetrapeptides Modelled to the Androgen Binding Site of ZIP9 Stimulate Expression of Tight Junction Proteins and Tight Junction Formation in Sertoli Cells

Androgens stimulate the expression of tight junction (TJ) proteins and the formation of the blood-testis barrier (BTB). Interactions of testosterone with the zinc transporter ZIP9 stimulate the expression of TJ-forming proteins and promote TJ formation in Sertoli cells. In order to investigate androgenic effects mediated by ZIP9 but not by the nuclear androgen receptor (AR), the effects of three tetrapeptides fitting the androgen binding site of ZIP9 were compared with those induced by testosterone in a Sertoli cell line expressing ZIP9 but not the AR. Three tetrapeptides and testosterone displaced testosterone-BSA-FITC from the surface of 93RS2 cells and stimulated the non-classical testosterone signaling pathway that includes the activation of Erk1/2 kinases and transcription factors CREB and ATF-1. The expression of the TJ-associated proteins ZO-1 and claudin-5 was triggered as was the re-distribution of claudin-1 from the cytosol to the membrane and nucleus. Furthermore, TJ formation was stimulated, indicated by increased transepithelial electrical resistance. Silencing ZIP9 expression by siRNA prevented all of these responses. These results are consistent with an alternative pathway for testosterone action at the BTB that does not involve the nuclear AR and highlight the significant role of ZIP9 as a cell-surface androgen receptor that stimulates TJ formation.

Adenylyl cyclase 3 deficiency results in dysfunction of blood-testis barrier during mouse spermiogenesis

Human infertility has become a global medical and social health problem. Mice deficient in type 3 adenylyl cyclase (AC3), a key enzyme that synthesizes cyclic adenosine monophosphate (cAMP), develop male infertility, although the underlying molecular mechanisms remain unknown. We performed a label-free quantitative (LFQ) proteomics analyses to identify testicular differentially expressed proteins (DEPs) and their respective biological processes. Furthermore, histological examination demonstrated that AC3 deficiency in mice led to mild impairment of spermatogenesis, including the thinning of seminiferous epithelium and local lesions in the testis. We further identified that the integrity of the blood-testis barrier (BTB) was impaired in AC3 knockout (AC3^-/-) mice accompanied with the reduction in the expression of tight junctions (TJs) and ectoplasmic specialization (ESs)-related proteins. In addition, the deletion of AC3 in mice also reduced the germ cell proliferation, increased apoptosis, and decreased lipid deposition in the seminiferous tubules. Collectively, our results revealed a role of AC3 in regulating the BTB integrity during spermatogenesis. Thus, our findings provide new perspectives for future research in male infertility.

Titanium dioxide nanoparticles perturb the blood-testis barrier via disruption of actin-based cell adhesive function

As one of the most commonly used nanoparticles, titanium dioxide nanoparticles (TiO₂-NPs) are widely used as coating reagents in cosmetics, medicine and other industries. The increasing risk of exposure to TiO₂-NPs raises concerns about their safety. In this study, we investigated the mechanism by which TiO₂-NPs cross the blood-testis barrier (BTB). TM-4 cells were selected as an in vitro Sertoli cell model of BTB. Cell viability, cell morphological changes, apoptosis, oxidative damage, and the expression levels of actin regulatory and tight junction (TJ) proteins were assessed in TM-4 cells treated with 3-nm and 24-nm TiO₂-NPs. Cells treated with 3-nm TiO₂-NPs exhibited increased cytotoxicity and decreased Annexin II expression, whereas cells treated with 24-nm TiO₂-NPs exhibited increased Arp 3 and c-Src expression. Both TiO₂-NPs induced significant oxidative stress, decreased the expression of TJ proteins (occludin, ZO-1 and claudin 5), damaged the TJ structure, and exhibited enlarged gaps between TM-4 cells. Our results indicated that both TiO₂-NPs crossed the BTB by disrupting actin-based adhesive junctions of TM-4 cells; however, apoptosis was not observed. Our results provide new insights into how TiO₂-NPs cross the BTB.

Protective effect of astragaloside IV on cadmium-induced spermatogenesis microenvironment damage in rats

The previous study using Sertoli cells cultured in vitro has shown that the protective effects of astragaloside IV (AsIV) on cadmium (Cd)-induced damage to Sertoli cells and its membrane proteins. Yet, it is not known if AsIV has an equivalent effect on Cd-induced damage to the spermatogenesis microenvironment in rats. Using an in vivo model, Cd-induced damage to the spermatogenesis microenvironment and the protective effects of AsIV were studied. Eighteen male Sprague Dawley (SD) rats were randomly divided into three groups (n = 6/group): Cd group, Cd&AsIV group, and control group. Cd was administered to the rats in the Cd group via i.p. at 1 mg/kg body weight once daily, Cd and AsIV was administered to the rats in the Cd&AsIV group via i.p. at 1 mg/kg body weight and 10 mg/kg body weight respectively once daily, and the same volume of saline was administered to the rats in control group via i.p. once daily. The rats in the three groups were injected continuously for 5 days. Vesicular formation in the seminiferous tubules was observed in the Cd treatment group. The average optical density of claudin-11, zonal occludin-1 (ZO-1), and connexin 43 (Cx43) decreased significantly in the Cd treatment group. The ultrastructural damage of the Sertoli cells and tight junctions were also observed by electron microscopy. AsIV treatment rescued the morphologic changes of the seminiferous tubules of the testis and the ultrastructural damage of the Sertoli cells and tight junctions. The average optical density of claudin-11, ZO-1, and Cx43 also increased significantly after AsIV treatment. Cd damages the spermatogenesis microenvironment in rats, which can be rescued by AsIV treatment. These results illustrate that AsIV may also have a protective effect on Cd-induced damage to the spermatogenesis microenvironment in rats.Abbreviations: AsIV: astragaloside IV; Cd: cadmium; SD: Sprague Dawley; ZO-1: zonal occludin-1; Cx43: connexin 43; BTB: blood-testis barrier; MAPKs: mitogen-activated protein kinases; OSP: oligodendrocyte-specific protein; Cxs: connexins; GJIC: gap junctional intercellular communication; ROS: reactive oxygen species; MDA: malondialdehyde; TGF: tumor growth factor; PBS: phosphate buffer saline; BSA: bovine serum albumin.

Therapeutic effects of thymoquinone or capsaicin on acrylamide-induced reproductive toxicity in rats mediated by their effect on oxidative stress, inflammation, and tight junction integrity

In the field of environmental toxicology, endocrine-disrupting effects have become a major concern. The present research set out to investigate the possible reproductive toxicity of acrylamide. The research was also expanded to explore the protective effects of two nutraceuticals, thymoquinone (TQ) and capsaicin, against acrylamide-induced reproductive toxicity. Six groups of sixty male albino rats were created. Group 1 was used as a control. Rats were administered a daily dose of acrylamide and acted as the model in Group 2. TQ was provided to rats once a day in Group 3. Capsaicin was administered to rats once a day in Group 4. TQ was given once daily to rats exposed to acrylamide in Group 5. Rats were given capsaicin once a day for eight weeks after being exposed to acrylamide in Group 6. Acrylamide induced oxidative stress, testicular NF-κB/p65 expression, and down-regulated the expression of occludin, all of which can contribute to its testicular toxicity, while TQ or capsaicin removes all of these toxicity signs. TQ and capsaicin have shown efficacy in alleviating all of the acrylamide's toxic insults in the current reproductive toxicity model. Both nutraceuticals upregulated the expression of occludin in testicular tissue and restored tight junction integrity, in addition to their well-known antioxidant and anti-inflammatory effects, which were confirmed in this study.

L-carnitine extenuates endocrine disruption, inflammatory burst and oxidative stress in carbendazim-challenged male rats via upregulation of testicular StAR and FABP9, and downregulation of P38-MAPK pathways

We have addressed in the current study the potential of L-carnitine (LC) to extenuate the reproductive toxic insults of carbendazim (CBZ) in male rats, and the molecular mechanisms whereby carnitine would modify the spermatogenic and steroidogenic derangements invoked by the endocrine disruptor. Herein, animals received daily doses of carbendazim (100 mg/kg) by gavage for 8 weeks. Another CBZ-challenged group was co-supplemented with LC (500 mg/kg, IP) twice weekly for 8 weeks. Sperm quantity and quality (morphology, motility and viability), serum testosterone and gonadotropins, and thyroid hormone levels were assessed. Serum tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6) and interleukin-10 (IL-10) concentrations were determined by ELISA. Oxidant/antioxidant status in rat testis was investigated via measuring testicular contents of malondialdehyde (MDA) and reduced glutathione (GSH), as well as the activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx). Immunohistochemical localizations of the junctional protein; occludin, and inflammatory markers; inducible nitric oxide synthase (iNOS) and nuclear factor kappa beta (NF-κB) were further analyzed. A host of transduction genes that regulate spermatogenic and steroidogenic pathways, and their encoded proteins namely, Steroidogenic Acute Regulatory Protein (StAR), Fatty acid binding protein 9 (FABP9) and P38-mitogen activated protein kinase (P38-MAPK) were assessed by real time quantitative (RT-qPCR) and Western blot. LC improved rat spermiogram, testicular histological alterations and endocrine perturbances, and modulated genes' expressions and their respective proteins. In conclusion, LC effects appear to reside for the most part on its endocrine-preserving, anti-oxidant and anti-inflammatory properties through a myriad of interlaced signal transductions that ultimately recapitulated its beneficial effects on spermatogenesis and steroidogenesis.

Chronic unpredictable stress disturbs the blood-testis barrier affecting sperm parameters in mice

RESEARCH QUESTION

Does chronic stress affect the key proteins and sperm parameters of the blood-testis barrier (BTB)?

DESIGN

C57Bl/6 mice were divided into two groups: a non-treated control group and a chronic unpredictable stress (CUS) applied group. The stress status of the animals was confirmed with behavioural tests. Histopathologic evaluation was conducted by haematoxylin and eosin staining and electron microscope. Malondialdehyde, corticosterone and testosterone levels were evaluated in peripheral blood. Expression levels of BTB proteins, namely zonula occludens-1 (ZO-1), claudin-11 (CLDN11) and clathrin in Sertoli cells, were assessed by Western blotting and immunofluorescence techniques. Sperm samples were collected from cauda epididymis, and sperm parameters analysed.

RESULTS

The stress model was confirmed by behavioural tests. Histopathological evaluation of the testes demonstrated a mild degeneration in seminiferous tubules. Malondialdehyde (P = 0.008) and corticosterone levels increased (P = 0.004) and testosterone levels decreased (P = 0.005) in the CUS group. Electron microscopic evaluation confirmed the damage in BTB integrity in the CUS group. Western blot analysis showed that ZO-1 and CLDN11 levels were significantly decreased, although clathrin levels were unchanged. Although sperm concentration and total motility rate were not significantly different between the groups, progressive motility (P = 0.03), normal sperm morphology (P = 0.04), chromatin integrity (toluidine blue) (P = 0.002) and the acrosomal reaction rate (P = 0.002) were significantly decreased, and acrosomal abnormality rate was dramatically increased (P = 0.04) in the CUS group.

CONCLUSIONS

In mice, CUS disrupted BTB integrity and impaired sperm parameters. A decrease in ZO-1 and CLDN11 expression levels may be proposed as the causative factor.

Nutrient restriction synergizes with retinoic acid to induce mammalian meiotic initiation in vitro

The molecular machinery and chromosome structures carrying out meiosis are frequently conserved from yeast to mammals. However, signals initiating meiosis appear divergent: while nutrient restriction induces meiosis in the yeast system, retinoic acid (RA) and its target Stra8 have been shown to be necessary but not sufficient to induce meiotic initiation in mammalian germ cells. Here, we use primary culture of mouse undifferentiated spermatogonia without the support of gonadal somatic cells to show that nutrient restriction in combination with RA is sufficient to induce Stra8- and Spo11-dependent meiotic gene and chromosome programs that recapitulate the transcriptomic and cytologic features of in vivo meiosis. We demonstrate that neither nutrient restriction nor RA alone exerts these effects. Moreover, we identify a distinctive network of 11 nutrient restriction-upregulated transcription factor genes, which are associated with early meiosis in vivo and whose expression does not require RA. Our study proposes a conserved model, in which nutrient restriction induces meiotic initiation by upregulating key transcription factor genes for the meiotic gene program and provides an in vitro platform for meiotic induction that could facilitate research and haploid gamete production.

The Molecular Mechanism of Sex Hormones on Sertoli Cell Development and Proliferation

Sustaining and maintaining the intricate process of spermatogenesis is liable upon hormones and growth factors acting through endocrine and paracrine pathways. The Sertoli cells (SCs) are the major somatic cells present in the seminiferous tubules and are considered to be the main regulators of spermatogenesis. As each Sertoli cell supports a specific number of germ cells, thus, the final number of Sertoli cells determines the sperm production capacity. Similarly, sex hormones are also major regulators of spermatogenesis and they can determine the proliferation of Sertoli cells. In the present review, we have critically and comprehensively discussed the role of sex hormones and some other factors that are involved in Sertoli cell proliferation, differentiation and maturation. Furthermore, we have also presented a model of Sertoli cell development based upon the recent advancement in the field of reproduction. Hence, our review article provides a general overview regarding the sex hormonal pathways governing Sertoli cell proliferation and development.

Review of COVID-19 and male genital tract

COVID‐19 pandemic leads to health challenges globally, and its diverse aspects need to be uncovered. Multi‐organ injuries have been reported by describing potential SARS‐CoV‐2 entrance routes: ACE2 and TMPRSS2. Since these cell surface receptors’ expression has been disclosed within the male reproductive system, its susceptibility to being infected by SARS‐CoV‐2 has been summarised through this literature review. Expression of ACE2 and TMPRSS2 at RNA or protein level has been reported across various investigations indicates that the male genitalia potentially is vulnerable to SARS‐CoV‐2 infection. Presence of SARS‐CoV‐2 within semen samples and following direct viral damage, secondary inflammatory response causing orchitis or testicular discomfort and finally the amount of viral load leading testicular damage and immune response activation are among probable underlying mechanisms. Therefore, genital examination and laboratory tests should be considered to address the male reproductive tract complications and fertility issues.

Intratesticular Peptidyl Prolyl Isomerase 1 Protein Delivery Using Cationic Lipid-Coated Fibroin Nanoparticle Complexes Rescues Male Infertility in Mice

Male infertility is a multifactorial condition. Unexplained male infertility is often caused by spermatogenesis dysfunction. Knockout of Pin1, an important regulator of cell proliferation and differentiation, produces male infertility phenotypes such as testicular immaturity and azoospermia with spermatogonia depletion and blood-testis barrier (BTB) dysfunction. Gene therapy has been clinically considered for the treatment of male infertility, but it is not preferred because of the risks of adverse effects in germ cells. Direct intracellular protein delivery using nanoparticles is considered an effective alternative to gene therapy; however, in vivo testicular protein delivery remains a pressing challenge. Here, we investigated the direct intracellular protein delivery strategy using a fibroin nanoparticle-encapsulated cationic lipid complex (Fibroplex) to restore intratesticular PIN1. Local intratesticular delivery of PIN1 via Fibroplex in Pin1 knockout testes produced fertile mice, achieving recovery from the infertile phenotypes. Mechanistically, PIN1-loaded Fibroplex was successfully delivered into testicular cells, including spermatogonial cells and Sertoli cells, and the sustained release of PIN1 restored the gene expression required for the proliferation of spermatogonial cells and BTB integrity in Pin1 knockout testes. Collectively, testicular PIN1 protein delivery using Fibroplex might be an effective strategy for treating male infertility.

Augmented oxidative stress and reduced mitochondrial function in ageing goat testis

Recently, there is a significant increase in the commercial use of goat products. Nevertheless, there are very few reports on the characterization of redox biomarkers and mitochondrial function in the goat testis. Therefore, in this study we studied the markers of oxidative stress and mitochondrial functions in the goat testis during the process of ageing. Alterations in the markers of oxidative stress/redox biomarkers (contents of reactive oxygen species, nitrite, lipid peroxide, protein carbonyl, glutathione and activities of glutathione peroxidase, monoamine oxidase) and mitochondrial function (Complex‐I and Complex‐IV activities) were elucidated during the process of ageing. Augmented oxidative stress and decreased mitochondrial function were prominent during ageing in the goat testis. Ageing can lead to induction of oxidative stress and decreased production of ATP; however, the prooxidants generated must be effectively removed from the body by the innate antioxidant defence system to minimize the damage to the host tissue. Conversely, the antioxidants cannot completely scavenge the excessive amount of reactive oxygen species produced during ageing or pathological conditions leading to significant cell death and tissue damage. Thus, the use of effective and potent antioxidants in the feed could significantly reduce oxidative stress and improve mitochondrial function, resulting in enriched goat health.

The Cellular Impact of the ZIKA Virus on Male Reproductive Tract Immunology and Physiology

Zika virus (ZIKV) has been reported by several groups as an important virus causing pathological damage in the male reproductive tract. ZIKV can infect and persist in testicular somatic and germ cells, as well as spermatozoa, leading to cell death and testicular atrophy. ZIKV has also been detected in semen samples from ZIKV-infected patients. This has huge implications for human reproduction. Global scientific efforts are being applied to understand the mechanisms related to arboviruses persistency, pathogenesis, and host cellular response to suggest a potential target to develop robust antiviral therapeutics and vaccines. Here, we discuss the cellular modulation of the immunologic and physiologic properties of the male reproductive tract environment caused by arboviruses infection, focusing on ZIKV. We also present an overview of the current vaccine effects and therapeutic targets against ZIKV infection that may impact the testis and male fertility.

Progress in translational reproductive science: testicular tissue transplantation and in vitro spermatogenesis

Since the birth of the first child conceived via in vitro fertilization 40 years ago, fertility treatments and assisted reproductive technology have allowed many couples to reach their reproductive goals. As of yet, no fertility options are available for men who cannot produce functional sperm, but many experimental therapies have demonstrated promising results in animal models. Both autologous (stem cell transplantation, de novo morphogenesis, and testicular tissue grafting) and outside-the-body (xenografting and in vitro spermatogenesis) approaches exist for restoring sperm production in infertile animals with varying degrees of success. Once safety profiles are established and an ideal patient population is chosen, some of these techniques may be ready for human experimentation in the near future, with likely clinical implementation within the next decade.

Variation analysis of SOX8 gene in Chinese men with non-obstructive azoospermia or oligozoospermia

Sox8, encoding a SRY-related HMG box transcription factor, is essential in Sertoli cells for germ cell differentiation via regulation of integrity of the blood-testis barrier (BTB) as well as Sertoli-germ cell adhesion. Inactivation of Sox8 gene in mice causes postnatal progressive spermatogenic failure, resulting in male infertility. This study aims to investigate whether variants of SOX8 contribute to pathogenesis of idiopathic non-obstructive azoospermia (NOA) or oligozoospermia. A case-control genetic study was conducted in which all exons and exon-intron boundaries of SOX8 gene were screened in 190 NOA and 139 oligozoospermia cases by Sanger sequencing. The detected variants were examined in 284 normospermic controls. Nine known single-nucleotide polymorphisms (SNPs) of SOX8 gene were identified, and four of them exist simultaneously in oligo/azoospermia patients. A comparison of allele/genotype frequencies of these variants showed no significant difference between oligo/azoospermia cases and controls. The results indicate that deleterious variants in SOX8 gene may not be a common cause for oligo/azoospermia in Chinese men. Considering ethnic diversity, SOX8 could not be ruled out as a candidate gene for male infertility. The role of SOX8-mediated Sertoli cell function and BTB integrity played in the pathogenesis of male infertility needs to be further explored in other populations.

Wild-type p53-induced phosphatase 1 (WIP1) regulates the proliferation of swine Sertoli cells through P53

Wild-type p53-induced phosphatase 1 (WIP1) plays an oncogenic function by increasing cell proliferation in various cancer types. Deficiency in WIP1 expression leads to male infertility, possibly by impairing the blood-testis barrier and spermatogenesis. However, how WIP1 functions in the Sertoli cells to affect male reproduction remains unclear. Thus, in the present study we used a swine Sertoli cell line to investigate whether WIP1 regulated the proliferation of Sertoli cells to participate in male reproduction. The WIP1 inhibitor GSK2830371, WIP1-short interference (si) RNAs and an upstream microRNA (miR-16) were used to inhibit the expression of WIP1, after which the proliferation of swine Sertoli cells, P53 expression and the levels of P53 phosphorylation were determined. Inhibiting WIP1 expression suppressed swine Sertoli cell proliferation, increased P53 expression and increased levels of P53 phosphorylation. In addition, overexpression of miR-16 in swine Sertoli cells resulted in a decrease in WIP1 expression and increases in both P53 expression and P53 phosphorylation. Together, these findings suggest that WIP1 positively regulates the proliferation of swine Sertoli cells by inhibiting P53 phosphorylation, and the miR-16 is likely also involved by targeting WIP1.

The testis-specific expressed gene Spata34 is not required for fertility in mice

It is estimated that more than two thousand genes exhibit testis-predominant expression pattern. The functions of hundreds of these genes have been explored during mouse spermatogenesis. However, there are still many genes whose relevance to reproduction in vivo remains unexplored. Our previous studies, as well as the other documented study, have indicated that Spata34, an evolutionarily conserved gene in metazoan species, was exclusively expressed in mouse testes and involved in spermatogenesis by regulating cell cycle progression. The present study aims to determine the effect of Spata34 gene knockout on mouse reproduction in vivo by generating a Spata34 gene knockout model using CRISPR/Cas9-mediated genome editing technology. We found that the Spata34 gene KO mice had normal fertility compared with wild type mice, and no overt detectable difference was found in testis/body weight ratios, testicular histology, sperm counts and spermatozoa motility parameters between WT and Spata34 KO mice. Our report indicated that the testis-specific-expressed gene Spata34 was not required for male mouse fertility, which will help to avoid unnecessary expenditures and effort by other researchers.

Landscape of RNA editing reveals new insights into the dynamic gene regulation of spermatogenesis

Spermatogenesis is an important physiological process associated with male infertility. As a kind of post-transcriptional regulation, RNA editings (REs) change the genetic information at the mRNA level. But whether there are REs and what's the role of REs during the process are still unclear. In this study, we integrated published RNA-Seq datasets and established a landscape of RNA REs during the development of mouse spermatogenesis. Totally, 7530 editing sites occurred in 2012 genes among all types of male germ cells were found, these sites enrich on some regions of chromosomes, including chromosome 17 and both ends of chromosome Y. We also found about half of the REs in CDSs can cause amino acids changes. Some non-synonymous REs which exist in specific genes may play important roles in spermatogenesis. Finally, we verified a non-synonymous A-to-I RNA editing site in Cog3 and a stoploss editing in Tssk6 during spermatogenesis. In short, we systematically analyzed the dynamic landscape of RNA editing at different stages of spermatogenesis.

Experimental dapsone administration induces infertility in male Wistar rats: Mechanisms and clinical implications

Dapsone (4, 4'-diaminodiphenylsulfone, DDS) is a potent anti-inflammatory and antibacterial compound which has been used in the treatment of leprosy, vasculitis and dermatitis herpetiformis, lupus erythematosus profundus and even as an antimalarial in combination with proguanil. This study investigated the effect of the administration of dapsone on the reproductive activities of male rats using in vivo and in vitro techniques. In the in vivo study, dapsone was administered orally to male Wistar rats for 5 days or 6 weeks after which their body weight, relative reproductive organ weights, sperm parameters and reproductive hormones were determined while testicular and epididymal histology were also assessed. Data were compared using analysis of variance and Students-Newman-Keuls multiple comparison test. For the in vitro study, Sertoli cells were cultured and treated with varying doses of dapsone at different durations, thereafter Sertoli cell viability and nuclei integrity were determined. Also, the genetic expressions of Glial cell line-derived neurotrophic factor (GDNF) and transferrin were assessed. The results obtained from the in vivo study showed a duration-dependent significant decrease in body and reproductive organ weights, sperm parameters and serum testosterone concentration. Testicular and epididymal histology also showed duration-dependent degenerative changes. However, all these changes were restored towards control values in the recovery experiment. The viability and deoxyribonucleic acid (DNA) integrity of the treated Sertoli cells showed dose and duration-dependent adverse effects while GDNF and transferrin showed normal genetic expressions. These results suggest that dapsone could induce male reproductive stress by affecting testicular and epididymal structure and function.

Epigenetic transgenerational inheritance of testis pathology and Sertoli cell epimutations: generational origins of male infertility

Male reproductive health has been in decline for decades with dropping sperm counts and increasing infertility, which has created a significant societal and economic burden. Between the 1970s and now, a general decline of over 50% in sperm concentration has been observed in the population. Environmental toxicant-induced epigenetic transgenerational inheritance has been shown to affect testis pathology and sperm count. Sertoli cells have an essential role in spermatogenesis by providing physical and nutritional support for developing germ cells. The current study was designed to further investigate the transgenerational epigenetic changes in the rat Sertoli cell epigenome and transcriptome that are associated with the onset of testis disease. Gestating female F0 generation rats were transiently exposed during the period of fetal gonadal sex determination to the environmental toxicants, such as dichlorodiphenyltrichloroethane (DDT) or vinclozolin. The F1 generation offspring were bred (i.e. intercross within the lineage) to produce the F2 generation grand-offspring that were then bred to produce the transgenerational F3 generation (i.e. great-grand-offspring) with no sibling or cousin breeding used. The focus of the current study was to investigate the transgenerational testis disease etiology, so F3 generation rats were utilized. The DNA and RNA were obtained from purified Sertoli cells isolated from postnatal 20-day-old male testis of F3 generation rats. Transgenerational alterations in DNA methylation, noncoding RNA, and gene expression were observed in the Sertoli cells from vinclozolin and DDT lineages when compared to the control (vehicle exposed) lineage. Genes associated with abnormal Sertoli cell function and testis pathology were identified, and the transgenerational impacts of vinclozolin and DDT were determined. Alterations in critical gene pathways, such as the pyruvate metabolism pathway, were identified. Observations suggest that ancestral exposures to environmental toxicants promote the epigenetic transgenerational inheritance of Sertoli cell epigenetic and transcriptome alterations that associate with testis abnormalities. These epigenetic alterations appear to be critical factors in the developmental and generational origins of testis pathologies and male infertility.

Npat-dependent programmed Sertoli cell proliferation is indispensable for testis cord development and germ cell mitotic arrest

As the major somatic cell type, Sertoli cells undergo active proliferation and play essential roles to establish testis cord at fetal stage. They also function to maintain germ cell development throughout the life of testicular development. However, the significance of Sertoli cell number for testis cord development and gonocyte fate is still unclear. Nuclear protein ataxia-telangiectasia (NPAT, also known as p220), a substrate of cyclin E/cyclin-dependent kinase 2, is well known as a regulator of cell proliferation through regulating histone expression. To study the role of NPAT during Sertoli cell development, we generated a mouse strain carrying conditional floxed Npat alleles, when crossing with anti-Müllerian hormone-cre, leading to the specific deletion of Npat in Sertoli cells. Npat disruption in Sertoli cells inhibited the programmed proliferation of fetal Sertoli cells resulting in disruption of developing testis cords, and subsequent postnatal mutant testes were severely hypoplastic. Germ cells, which are presumed to be in quiescent status during perinatal stage, exited G0 phase arrest and re-enter mitotic cell cycle prematurely. Of particular note, some germ cells possessed the meiotic signal in Npat-deficient testes. Our data thus indicates that the function of Npat-dependent Sertoli cells is essential at multiple steps in testis development, and this study also identifies Sertoli cells as a major regulator of germ cell development, which are required to maintain a local growth niche to repress premature mitosis and meiosis of gonocytes.-Jiang, X., Yin, S., Fan, S., Bao, J., Jiao, Y., Ali, A., Iqbal, F., Xu, J., Zhang, Y., Shi, Q. Npat-dependent programmed Sertoli cell proliferation is indispensable for testis cord development and germ cell mitotic arrest.

Adverse effects of bisphenol A on Sertoli cell blood-testis barrier in rare minnow Gobiocypris rarus

Bisphenol A (BPA), an environmental contaminant, has been shown to disturb the dynamics of Sertoli cell blood-testis barrier (BTB) in mammal testis. However, the effects of BPA on Sertoli cell barrier (SC barrier) were little known in fish to date. To evaluate the potential mechanism of reproductive toxicity of BPA, we studied the damage of SC barrier using in vivo models. In this study, male adult rare minnow Gobiocypris rarus were exposed to 15 μg/L BPA for 7-35 days. Gonadal histology and the integrity of SC barrier were analyzed. Meanwhile, the expressions of SC barrier -associated proteins, tumor necrosis factor (TNFα) content, and the mRNA expressions of genes in the mitogen activated protein kinase (MAPK) pathway were detected. Histological analysis demonstrated 15 μg/L BPA promoted the infiltration of inflammatory cells in fish testes after 7-days exposure. The biotin tracer assay showed that 7-days BPA exposure increased permeability for spermatid cysts. In addition, the BPA treatment caused increased TNFα in testis, which was reportedly related to SC barrier impairment. The expressions of Occludin and β-Catenin protein were significantly decreased in the testes after 7- and 21-days exposure. BPA also altered the mRNA expressions of occludin, β-catenin, p38 MAPK and JNK. Therefore, the detrimental effects of BPA on reproduction of male fish may attribute to the disturbed expressions of SC junction proteins.

Gliclazide alone or in combination with atorvastatin ameliorated reproductive damage in streptozotocin-induced type 2 diabetic male rats

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High-fat diet/STZ-induced T2DM caused severe damage in rat male reproductive system.

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ATV treatment slightly improved the reproductive functions.

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GLZ treatment strongly ameliorated spermatogenesis as well as testicular structure.

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ATV/GLZ combination treatment improved sperm morphology and testes structure.

Objectives

Type 2 diabetes (T2DM) is one of the most serious challenges of the 21th century with life-threatening complications and excessive health care costs. In diabetic patients, the main goal in T2DM treatment is the regulation of both blood glucose and lipid levels. For that, Gliclazide (GLZ), an oral antidiabetic, and Atorvastatin (ATV), a lipid lowering agent, are widely used drugs as combination. Diabetes has been reported severe impacts on male reproductive system; however, data obtained about ATV and GLZ treatment alone or in combination are conflicted or insufficient. Herein the effects of ATV and GLZ on male reproductive system in type 2 diabetic male rats have been investigated in the present study.

Methods

T2DM was induced by high-fat diet and single injection of streptozotocin (STZ) (35 mg/kg) in young adult male Sprague-Dawley rats. The diabetic rats were given ATV (10 mg/kg), GLZ (10 mg/kg) and ATV/GLZ (1:1, 10 mg/kg) combination by oral gavage for 28 days. The hormone levels were determined in the cardiac blood samples; and the histopathological and ultrastructural analyses were conducted in the testicular tissues and epididymal sperms.

Results

It was observed that diabetes had severe effects on testicular tissue and spermatogenesis. ATV treatment did not affect sperm count and testes structure (p > 0.05), however ameliorated sperm morphology (p < 0.05). GLZ treatment increased sperm count, and improved sperm morphology, testes structure and spermatogenesis (p < 0.05). ATV/GLZ combination treatment enhanced sperm morphology and improved testicular structure (p < 0.05) while did not affect sperm count (p > 0.05).

Conclusion

GLZ treatment regenerated testicular damage and sperm parameters whether alone or in combination with ATV in diabetic rats without affecting hypothalamic-pituitary-gonadal axis.