Inflammatory networks in the control of spermatogenesis : chronic inflammation in an immunologically privileged tissue?

Reduction of osteoclast formation and survival following suppression of cytokines by diacerein in periodontitis

Periodontitis causes an increase in several bioactive agents such as interleukins (IL), tumor necrosis factor (TNF)-α and receptor activator of NF-kB ligand (RANKL), which induce the osteoclast formation and activity. Since diacerein exerts anti-TNF-α and anti-IL-1 effects, alleviating bone destruction in osteoarthritis, we investigated whether this drug inhibits the formation and survival of osteoclast in the periodontitis. Rats were distributed into 3 groups: 1) group with periodontitis treated with 100 mg/kg diacerein (PDG), 2) group with periodontitis treated with saline (PSG) and group control (CG) without any treatment. After 7, 15 and 30 days, the maxillae were collected for light and transmission electron microscopy analyses. Gingiva samples were collected to evaluate the mRNA levels for Tnf, Il1b, Tnfsf11 and Tnfrsf11b by RT-qPCR. In PDG, the expression of Tnf and Il1b genes reduced significantly compared to PSG, except for Tnf expression at 7 days. The number of osteoclasts reduced significantly in the PDG in comparison with PSG at 7 and 15 days. In all periods, the IL-6 immunoexpression, RANKL/OPG immunoexpression and mRNA levels of Tnfsf11/Tnfrsf11b ratio were significantly lower in PDG than in PSG. PDG exhibited significantly higher frequency of TUNEL-positive osteoclasts than in PSG and CG at all time points. Osteoclasts with caspase-3-immunolabelled cytoplasm and nuclei with masses of condensed chromatin were observed in PDG, confirming osteoclast apoptosis. Diacerein inhibits osteoclastogenesis by decreasing Tnf and Il1b mRNA levels, resulting in decreased RANKL/OPG ratio, and induces apoptosis in osteoclasts of alveolar process of rat molars with periodontitis.

Molecular mechanisms of cellular dysfunction in testes from men with non-obstructive azoospermia

Male factor infertility affects 50% of infertile couples worldwide; the most severe form, non-obstructive azoospermia (NOA), affects 10-15% of infertile males. Treatment for individuals with NOA is limited to microsurgical sperm extraction paired with in vitro fertilization intracytoplasmic sperm injection. Unfortunately, spermatozoa are only retrieved in ~50% of patients, resulting in live birth rates of 21-46%. Regenerative therapies could provide a solution; however, understanding the cell-type-specific mechanisms of cellular dysfunction is a fundamental necessity to develop precision medicine strategies that could overcome these abnormalities and promote regeneration of spermatogenesis. A number of mechanisms of cellular dysfunction have been elucidated in NOA testicular cells. These mechanisms include abnormalities in both somatic cells and germ cells in NOA testes, such as somatic cell immaturity, aberrant growth factor signalling, increased inflammation, increased apoptosis and abnormal extracellular matrix regulation. Future cell-type-specific investigations in identifying modulators of cellular transcription and translation will be key to understanding upstream dysregulation, and these studies will require development of in vitro models to functionally interrogate spermatogenic niche dysfunction in both somatic and germ cells.

Frequency, morbidity and equity - the case for increased research on male fertility

Currently, most men with infertility cannot be given an aetiology, which reflects a lack of knowledge around gamete production and how it is affected by genetics and the environment. A failure to recognize the burden of male infertility and its potential as a biomarker for systemic illness exists. The absence of such knowledge results in patients generally being treated as a uniform group, for whom the strategy is to bypass the causality using medically assisted reproduction (MAR) techniques. In doing so, opportunities to prevent co-morbidity are missed and the burden of MAR is shifted to the woman. To advance understanding of men's reproductive health, longitudinal and multi-national centres for data and sample collection are essential. Such programmes must enable an integrated view of the consequences of genetics, epigenetics and environmental factors on fertility and offspring health. Definition and possible amelioration of the consequences of MAR for conceived children are needed. Inherent in this statement is the necessity to promote fertility restoration and/or use the least invasive MAR strategy available. To achieve this aim, protocols must be rigorously tested and the move towards personalized medicine encouraged. Equally, education of the public, governments and clinicians on the frequency and consequences of infertility is needed. Health options, including male contraceptives, must be expanded, and the opportunities encompassed in such investment understood. The pressing questions related to male reproductive health, spanning the spectrum of andrology are identified in the Expert Recommendation.

Insight into inflammation involvement in varicocele: A narrative review

BACKGROUND

Varicocele is one of the main causes of male infertility. Although the pathophysiology mechanism of varicocele is very well described and understood, there are some unanswered questions that remains unknown. Some studies have previously described the state of testicular inflammation and sperm in animal models, especially the mouse model, and the seminal plasma of men with varicocele, with or without changes in semen parameters.

METHODS OF STUDY

This review intended to verify the role of inflammatory mechanism in varicocele, using clinical studies as well as animal model studies on the effect of inflammation caused by varicocele on the function of testicular somatic and germ cells.

RESULTS

In-vivo studies confirmed whether anti-inflammatory molecules could treat the semen of men with varicocele and rats with varicocele. The use of different anti-inflammatory agents in mouse model studies provided a new perspective for future clinical studies to investigate the effect of concurrent treatment with surgery to improve surgical outcomes.

CONCLUSION

Similar to animal model studies, previously conducted clinical trials have demonstrated the effectiveness of anti-inflammatory therapy in varicocele patients. However, clinical trials using anti-inflammatory are needed to be conducted agents to evaluate different aspects of this therapeutical approach in varicocele patients.

Variation in immuno-reproductive milieu of testis in Clarias magur from pre-spawning to spawning phase: An indication towards non-canonical role of immune elements in testes

Immune mechanisms are major players in ensuring the normal functioning of testicular functions. However, apart from their role in active defence against pathogens, prior studies have also suggested a possibility for reproduction-related (non-immune) functions of certain immune elements. This study employs a comparative transcriptomics approach followed by network analysis for tracking the variation in the immuno-reproductive milieu of Clarias magur testis in spawning versus pre-spawning phase. The results show a significant modulation of both reproduction and immune-relevant genes in spawning versus pre-spawning phase. The functional enrichment of the upregulated reproduction-relevant gene network also shows immune-related biological processes which indicates a probability of involvement of these candidates in spermatogenesis-related events for switching from pre-spawning to spawning phase. The upregulated immune network is highly dense with 40 hubs, 10 cluster sub-networks and 142 functionally enriched pathways in comparison to its downregulated counterpart with only 5 hubs, 1 cluster and 1 enriched pathway. These findings indicate that the synchronisation in modulation of both reproductive and immune-related factors is critical for progression of testicular events guiding the switch from pre-spawning to spawning phase. The reproductive phase-dependent variation in plasma sex steroid levels and the selected genes for quantitative PCR also corroborated this hypothesis. The study also serves as a preliminary screening step for probable immune candidates that may be involved in reproductive functions of testis in addition to defence.

Elderberry Diet Restores Spermatogenesis in the Transient Scrotal Hyperthermia-Induced Mice

Over the past years, several studies have also reported the adverse effects of hyperthermia on normal testicular tissues in several species including mice, rats, and humans. These deleterious impacts include temporarily drop in relative weight of testis along with a temporary partial or complete infertility. Sambucus nigra, also known as elderberry or sweet elder, is a source of bioactive compounds that has drawn growing attention for its potential beneficial effects in preventing and treating several diseases. This experimental research divided 30 mice into the following three groups: (1) control, (2) hyperthermia, and (3) hyperthermia receiving elderberry diet for 35 days. Scrotal hyperthermia was induced by water bath with 43 °C for 30 min. Then, the mice were euthanized, and their sperm samples were collected for sperm parameters analysis. Then, we took the testis samples for histopathological experimentations, immunohistochemistry against TNF-α and caspase-3 and serum testosterone, FSH and LH levels. Our outputs indicated that elderberry diet could largely improve the sperms parameters and stereological parameters, like spermatogonia, primary spermatocyte, round spermatid, and Leydig cells together with an increasing level of the serum testosterone compared to the scrotal hyperthermia induced mice. In addition, it was found that the expression of TNF-α and caspase-3 significantly decreased in the treatment groups by elderberry diet compared to the scrotal hyperthermia-induced mice. In conclusion, it could be concluded that elderberry diet may be regarded as an alternative treatment for improving the spermatogenesis process in the scrotal hyperthermia induced mice.

Two complementary approaches for efficient isolation of Sertoli cells for transcriptomic analysis

Sertoli cells (SCs) are the only somatic cells that reside in seminiferous tubules of testis. They directly interact with and support the development of germ cells, thus have an indispensable role in the process of spermatogenesis. SCs first appear in a proliferative state and then, with the initiation of the first wave of spermatogenesis, progress to a mature “nurturing” state which supports lifelong continuous sperm production. During this development, the SC transcriptome must adapt rapidly as obstacles in SC maturation often result in deficiencies in male fertility. Due to its importance in spermatogenesis, a reliable, rapid, and precise method for the isolation of high purity, viable and unadulterated SC has been largely missing. We have developed an improved method for the preparation of a testicular single cell suspension comprised of two alternative protocols to separate SCs from the rest of the testicular cells by FACS. The first sorting scheme is based on their co-expression of surface specific markers, FSHr and Occludin-1, while the second focuses on the co-staining of SCs with FSHr-specific antibody and Hoechst 33342, which discriminates DNA content of testicular cells. The entire procedure can be completed in less than 3 h which permits the analysis of the development-related transcriptional profile of these cells. Notably, our comparative study showed that this method resulted in a SC transcriptome that is largely comparable to SCs which were briskly isolated due to their cell-specific expression of fluorescent protein. Interestingly, we also show that SCs sorted as FSHr⁺Occludin⁺ cells contained a tangible portion of transcripts from all types of testicular germ cells. Sorting of SCs according to their 2C DNA content significantly reduced the presence of these transcripts, thus seems to be the most suitable approach for accurate determination of the SC transcriptome. We believe that these novel approaches for the isolation of SCs will assist researchers in the elucidation of their function as well as their role in spermatogenesis and disorders related to male infertility.

Echis ocellatus Venom-Induced Reproductive Pathologies in Rat Model; Roles of Oxidative Stress and Pro-Inflammatory Cytokines

This study reported reproductive pathologies associated with Echis ocellatus venom in animal model. Twenty male Wistar rats with body weight between 180 and 220 g were selected randomly into two groups (n = 10). Rats in group 1 served as the control while rats in group 2 were envenomed with a single intraperitoneal injection of 0.055 mg/kg−1 (LD6.25) of E. ocellatus venom on the first day and a repeated dose on the twenty fifth day. Both control and envenomed rats were monitored for fifty consecutive days. The venom caused a significant (p < 0.05) reduction in sperm motility, count, and volume, with increased sperm anomalies in envenomed rats compared to the control. Likewise, serum concentrations of male reproductive hormones were significantly (p < 0.05) higher in envenomed rats. Increased levels of malondialdehyde were accompanied by a significant (p < 0.05) decrease in reduced glutathione and catalase activity in the epididymis and testis tissues of envenomed rats. The venom enhanced the release of epididymal and testicular tumor necrosis factor-alpha and interleukin1-beta compared to the control. Furthermore, severe pathological defects were noticed in tissues of the testis and epididymis of envenomed rats. This study demonstrated that E. ocellatus venom toxins can induce reproductive dysfunction in male victims of snake envenoming.

The Search for Cancer Biomarkers: Assessing the Distribution of INDEL Markers in Different Genetic Ancestries

Cancer is a multifactorial group of diseases, being highly incident and one of the leading causes of death worldwide. In Brazil, there is a great variation in cancer incidence and impact among the different geographic regions, partly due to the genetic heterogeneity of the population in this country, composed mainly by European (EUR), Native American (NAM), African (AFR), and Asian (ASN) ancestries. Among different populations, genetic markers commonly present diverse allelic frequencies, but in admixed populations, such as the Brazilian population, data is still limited, which is an issue that might influence cancer incidence. Therefore, we analyzed the allelic and genotypic distribution of 12 INDEL polymorphisms of interest in populations from the five Brazilian geographic regions and in populations representing EUR, NAM, AFR, and ASN, as well as tissue expression in silico. Genotypes were obtained by multiplex PCR and the statistical analyses were done using R, while data of tissue expression for each marker was extracted from GTEx portal. We highlight that all analyzed markers presented statistical differences in at least one of the population comparisons, and that we found 39 tissues to be differentially expressed depending on the genotype. Here, we point out the differences in genotype distribution and gene expression of potential biomarkers for risk of cancer development and we reinforce the importance of this type of study in populations with different genetic backgrounds.

Cyclophosphamide instigated hepatic-renal oxidative/inflammatory stress aggravates immunosuppressive indoleamine 2,3-dioxygenase in male rats: Abatement by quercetin

The hepatic-renal toxicity associated with cyclophosphamide (CYP) treatment in both animals and humans have been reported. Quercetin, a dietary flavonoid, is known to elicit beneficial health effects. However, the influence of quercetin on the hepatic-renal toxicity associated with CYP-instigated indoleamine 2,3-dioxygenase is unavailable in the literature. The current study evaluated the effects of quercetin on the dysfunctional hepatic-renal status triggered by CYP exposure in rats. Experimental animals were exposed to CYP (100 mg/kg) or co-treated with quercetin (50 mg/kg) every other day for 7 days. Results revealed that quercetin treatment significantly assuaged CYP-mediated oxidative-inflammatory response, as well as augmenting serum levels of thyroid hormones. Additionally, quercetin attenuated CYP-induced reduction in antioxidant enzyme activities and enhanced hepatic-renal function markers, namely aspartate aminotransferase (AST), alanine aminotransferase (ALT), Alkaline phosphatase (ALP), and levels of urea and creatinine. Quercetin efficiently mitigated CYP-mediated increase in myeloperoxidase (MPO) activity, levels of nitric oxide and interleukin-6 (IL-6) in liver and kidney of rats. CYP-induced increase in the activities of immunosuppressive indoleamine 2, 3-dioxygenase (IDO) and tryptophan 2, 3-dioxygenase (TDO) in the tissues was abated in quercetin co-treated rats. In conclusion, Quercetin ameliorated deficits in the hepatic-renal function in CYP-exposed rats by lowering the activities/expression of immunosuppressive IDO and TDO via diminution of oxidative-inflammatory stress.

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

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

Pro-inflammatory cytokines and microRNAs in male infertility

Background

Male infertility is a problem that affects 10–15% of men of reproductive age. In particular, gametogenesis is a complex process in which inflammation may play a central role through the secretion of cytokines and the expression of microRNAs. We assessed the potential role of proinflammatory cytokines (TNF-α, IL-6 and IL-1α) and microRNAs (miR-146a-5p, miR-34a-5p and miR-23a-3p) in the seminal plasma of infertile men compared to controls, evaluating their correlation with seminal and biochemical parameters.

Methods and results

Expression of cytokines and microRNAs was analyzed by ELISA and q-PCR. Our data shows that IL-1α was significantly increased in the azoospermic group compared to controls, TNF-α mRNA was more expressed in the oligozoospermic group than controls. There were no significant differences in miRNAs expression among the three groups. The correlations between sperm parameters and inflammatory markers were evaluated, however no significance was highlighted.

Conclusions

The determination of each inflammatory marker separately in the seminal plasma of subfertile men, despite some significant differences, does not have a diagnostic value in male infertility even if an assay of selective pro-inflammatory cytokines and microRNAs in the semen may improve the diagnosis of male infertility.

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

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

The Role of TNF-α and Anti-TNF-α Agents during Preconception, Pregnancy, and Breastfeeding

Tumor necrosis factor-alpha (TNF-α) is a multifunctional Th1 cytokine and one of the most important inflammatory cytokines. In pregnancy, TNF-α influences hormone synthesis, placental architecture, and embryonic development. It was also shown that increased levels of TNF-α are associated with pregnancy loss and preeclampsia. Increased TNF-α levels in complicated pregnancy draw attention to trophoblast biology, especially migratory activity, syncytialisation, and endocrine function. Additionally, elevated TNF-α levels may affect the maternal-fetal relationship by altering the secretory profile of placental immunomodulatory factors, which in turn affects maternal immune cells. There is growing evidence that metabolic/pro-inflammatory cytokines can program early placental functions and growth in the first trimester of pregnancy. Furthermore, early pregnancy placenta has a direct impact on fetal development and maternal immune system diseases that release inflammatory (e.g., TNF-α) and immunomodulatory factors, such as chronic inflammatory rheumatic, gastroenterological, or dermatological diseases, and may result in an abnormal release of cytokines and chemokines in syncytiotrophoblasts. Pregnancy poses a challenge in the treatment of chronic disease in patients who plan to have children. The activity of the disease, the impact of pregnancy on the course of the disease, and the safety of pharmacotherapy, including anti-rheumatic agents, in pregnancy should be considered.

Chlorogenic acid co-administration abates tamoxifen-mediated reproductive toxicities in male rats: An experimental approach

Reports over the years have demonstrated toxic side effect-including reproductive toxicity- of tamoxifen (TAM), a drug of choice in the management of primary breast cancer. Chlorogenic acid (CGA), a dietary polyphenol, reportedly elicits beneficial pharmacological effects. However, the impact of CGA on TAM-associated reproductive toxicity is absent in the literature. We, therefore, experimented on CGA's effect and TAM-mediated reproductive toxicity in rats. Cohorts of rats were treated with TAM (50 mg/kg) or co-treated with CGA (25 or 50 mg/kg) for 14 consecutive days. The result showed that treatment of CGA significantly increases testosterone, LH, and FSH levels compared to the TAM group. However, prolactin level was markedly decreased after pretreatment of CGA in TAM-treated rats. CGA abated TAM-induced decreases acid phosphatase, alkaline phosphatase, and antioxidant enzymes in the testis. CGA alleviated TAM-facilitated surges of reactive oxygen and nitrogen species, myeloperoxidase, nitric oxide, interleukin-1β, and tumor necrosis factor-alpha in rats epididymis and testes. Additionally, CGA increased anti-inflammatory cytokine -interleukin-10-, suppressed caspase-3 activity, and reduced pathological lesions in the examined organs of rats co-treated with CGA and TAM. CGA phytoprotective effect improved reproductive function occasioned by TAM-mediated toxicities in rats, by abating oxido-inflammatory damages and downregulating apoptotic responses. PRACTICAL APPLICATIONS: CGA protects against the damaging oxido-inflammatory responses incumbent on TAM metabolism. As an antioxidant abundant in plant-derived foods, CGA reportedly protects against inflammatory damage, hypertension, and neurodegenerative diseases. We present evidence that CGA ameliorates TAM-induced reproductive dysfunction by suppressing oxidative and inflammation stress downregulate apoptosis and improve reproductive function biomarker in rats.

Gui-A-Gra Attenuates Testicular Dysfunction in Varicocele-Induced Rats via Oxidative Stress, ER Stress and Mitochondrial Apoptosis Pathway

Gui-A-Gra, a commercial insect powder from Gryllus bimaculatus, is registered as an edible insect by the Korean food and drug administration. The aim of this study was to investigate the effect of Gui-A-Gra on testicular damage induced by experimental left varicocele in male Sprague Dawley rats. A total of 72 rats were randomly divided into the following six groups (12 rats in each group): a normal control group (CTR), a group administrated with Gui-A-Gra 1.63 gm/kg (G1.63), a group administrated with Gui-A-Gra 6.5 gm/kg (G6.5), a varicocele (VC)-induced control group (VC), a VC-induced group administrated with Gui-A-Gra 1.63 gm/kg (VC + G1.63), and a VC-induced group administrated with Gui-A-Gra 6.5 gm/kg (VC + G6.5). Rats were administrated 1.63 or 6.5 gm/kg Gui-A-Gra once daily for 42 days. Indicators of sperm parameters, histopathology, reproductive hormones, oxidative stress, endoplasmic reticulum (ER) stress, inflammation, and mitochondrial apoptosis were analyzed to evaluate effects of Gui-A-Gra on VC-induced testicular dysfunction. Gui-A-Gra administration to VC-induced rats significantly (p < 0.05) increased sperm count and sperm motility, Johnsen score, spermatogenic cell density, serum testosterone, testicular superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase, GPx4, and steroidogenic acute regulatory protein (StAR) level. Moreover, pretreatment with Gui-A-Gra significantly (p < 0.05) decreased terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) positive cells/tubules, serum luteinizing hormone (LH), serum follicle-stimulating hormone (FSH), testicular tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), malondialdehyde (MDA), reactive oxygen species (ROS)/reactive nitrogen species (RNS) level, glucose-regulated protein-78 (Grp-78), phosphorylated c-Jun-N-terminal kinase (p-JNK), phosphorylated inositol-requiring transmembrane kinase/endoribonuclease 1α (p-IRE1α), cleaved caspase-3, and BCL2 associated X protein: B-cell lymphoma 2 (Bax: Bcl2) ratio in VC rats. These results suggest that protective effects of Gui-A-Gra on VC-induced testicular injury might be due to its antioxidant, anti-inflammatory, and androgenic activities that might be mediated via crosstalk of oxidative stress, ER stress, and mitochondrial apoptosis pathway.

Deoxynivalenol induced spermatogenesis disorder by blood-testis barrier disruption associated with testosterone deficiency and inflammation in mice

Deoxynivalenol (DON) is an unavoidable cereal crops contaminants and environmental pollutants, which seriously threated the health of human and animal. DON has been reported to exert significant toxicity effects on spermatogenesis, but the underlying mechanisms remain largely inconclusive. The blood-testis barrier (BTB) provides a specialized biochemical microenvironment for maintaining spermatogenesis. Thus, we hypothesized that DON could impair BTB and lead to spermatogenesis disorder. To confirm this hypothesis, sixty male mice were intragastrically administered with 0, 1.2, 2.4 and 4.8 mg/kg body weight DON for 28 days, and several important observations were obtained in present study. First, we found that DON induced spermatogenesis disorder, reflected by the declines of sperm concentration and quality, sperm ultrastructural damage as well as seminiferous tubular damage. Then, we proved that DON induced BTB disruption as well as decreased the expressions of BTB junction proteins, including Occludin, Connexin 43 and N-cadherin. Finally, the present study showed that DON induced inflammation and inhibited T biosynthesis in testis of mice. These results revealed that DON induced spermatogenesis disorder by BTB disruption associated with testosterone deficiency and inflammation in mice, which shed a new light on the potential mechanisms of reproductive toxicity induced by DON.

Anti-TNF agents and potential effects on male fertility: are men being counseled?

BACKGROUND

Adult men with autoimmune conditions are commonly prescribed anti-tumor necrosis factor (anti-TNF) agents; however, there is a paucity of quality evidence as to their effect on male fertility (e.g. semen parameters and sperm quality). Our objective was to determine if men with autoimmune conditions are being counseled regarding the unknown reproductive effects of anti-TNF agents prior to initiation of therapy.

METHODS

A retrospective analysis of 1010 male patients age 18-45 who were prescribed an anti-TNF agent were assessed for (1) receipt of counseling regarding potential reproductive effects; (2) screening for anatomic or laboratory abnormalities associated with infertility; (3) election for sperm cryopreservation.

RESULTS

Only 10.3% of men received counseling, and this was not associated with age (p = 0.77). Those who received counseling were significantly more likely to have a genitourinary exam performed, be assessed for presence of a varicocele, be asked about or endorse low libido or erectile dysfunction, have a testosterone, LH, FSH, or prolactin level checked, and have a semen analysis performed (all, p < 0.0001). Rates of sperm cryopreservation were low, but statistically higher in men who received counseling (5.77% (+) counseling, 1.10% (-) counseling) (p = 0.002).

CONCLUSIONS

The limited current literature lacks a consensus regarding the short- and long-term male reproductive effects of anti-TNF therapy. Despite this lack of clarity, rates of pre-initiation counseling were low. Rates of sperm cryopreservation, while improved in the counseled group remained low, suggesting prescribing physicians may be unaware of this option for patients.

How defective spermatogenesis affects sperm DNA integrity

Spermatogenesis is the essential process to maintain and promote male fertility. It is extraordinarily complex with many regulatory elements and numerous steps. The process involves several cell types, regulatory molecules, repair mechanisms and epigenetic regulators. Evidence has shown that fertility can be negatively impacted by reduced sperm DNA integrity. Sources of sperm DNA damage include replication errors and causes of DNA fragmentation which include abortive apoptosis, defective maturation and oxidative stress. This review outlines the process of spermatogenesis, spermatogonial regulation and sperm differentiation; additionally, DNA damage and currently studied DNA repair mechanisms in spermatozoon are also covered.

Differential gene regulation in selected lines for high and low sperm production in male guppies

In species where females mate with more than one male during the same reproductive event, males typically increase the number of sperm produced to boost their fertilization share. Sperm is not limitless, however, and theory predicts that their production will come at the cost of other fitness-related traits, such as body growth or immunocompetence, although these evolutionary trade-offs are notoriously difficult to highlight. To this end, we combined artificial selection for sperm production with a transcriptome analysis using Poecilia reticulata, a fish characterized by intense sperm competition in which the number of sperm transferred during mating is the most important predictor of fertilization success, yet sperm production is highly variable among males. We compared the brain and testes transcriptome in male guppies of lines artificially selected for high and low sperm production by identifying pivotal differentially expressed gene sets that may regulate spermatogenesis and immune function in this species. Despite the small differences in single genes' expression, gene set enrichment analysis showed coordinated gene expression differences associated with several pathways differentially regulated in the two selection lines. High sperm production males showed an upregulation of pathways related to immunosuppression and development of spermatozoa indicating a possible immunological cost of sperm production.

NC1-peptide regulates spermatogenesis through changes in cytoskeletal organization mediated by EB1

During the epithelial cycle of spermatogenesis, different sets of cellular events take place across the seminiferous epithelium in the testis. For instance, remodeling of the blood-testis barrier (BTB) that facilitates the transport of preleptotene spermatocytes across the immunological barrier and the release of sperms at spermiation take place at the opposite ends of the epithelium simultaneously at stage VIII of the epithelial cycle. These cellular events are tightly coordinated via locally produced regulatory biomolecules. Studies have shown that collagen α3 (IV) chains, a major constituent component of the basement membrane, release the non-collagenous (NC) 1 domain, a 28-kDa peptide, designated NC1-peptide, from the C-terminal region, via the action of MMP-9 (matrix metalloproteinase 9). NC1-peptide was found to be capable of inducing BTB remodeling and spermatid release across the epithelium. As such, the NC1-peptide is an endogenously produced biologically active peptide which coordinates these cellular events across the epithelium in stage VIII tubules. Herein, we used an animal model, wherein NC1-peptide cloned into the pCI-neo mammalian expression vector was overexpressed in the testis, to better understanding the molecular mechanism by which NC1-peptide regulated spermatogenic function. It was shown that NC1-peptide induced considerable downregulation on a number of cell polarity and planar cell polarity (PCP) proteins, and studies have shown these polarity and PCP proteins modulate spermatid polarity and adhesion via their effects on microtubule (MT) and F-actin cytoskeletal organization across the epithelium. More important, NC1-peptide exerted its effects by downregulating the expression of microtubule (MT) plus-end tracking protein (+TIP) called EB1 (end-binding protein 1). We cloned the full-length EB1 cDNA for its overexpression in the testis, which was found to block the NC1-peptide-mediated disruptive effects on cytoskeletal organization in Sertoli cell epithelium and pertinent Sertoli cell functions. These findings thus illustrate that NC1-peptide is working in concert with EB1 to support spermatogenesis.

MKP-1 attenuates LPS-induced blood-testis barrier dysfunction and inflammatory response through p38 and IκBα pathways

Sertoli cells create a local tolerogenic microenvironment to maintain testicular immune privilege especially through the formation of a blood-testis barrier (BTB). However, the molecular mechanisms underlying the immune modulation function and BTB dynamics of Sertoli cells remained elusive. MAP phosphatase (MKP)-1 acts as a crucial negative regulator of the inflammatory response. Nevertheless, the role of MKP-1 in regulating Sertoli cells has not been elucidated. In this study, we have for the first time uncovered distinct cellular localization of MKP-1 in the cells at different stages of mouse testis, and the level of MKP-1 expression was significantly up-regulated by LPS-induced acute testis inflammation. In addition, MKP-1 staining was strongly detected in nuclei and peri-nuclear regions of cytoplasm in the Sertoli cells, and it was presented at Sertoli cell tight junctions (TJs) at stages VII-VIII after LPS treatment. Moreover, we demonstrated that MKP-1 was capable of attenuating LPS-induced decrease of occludin by interaction with p38 MAP kinase and IκBα molecules. Taken together, our data highlight that MKP-1 was an important endogenous suppressor of innate immune responses involved in the regulation of BTB barrier dynamic. This study thus might offer novel targets for treating inflammatory diseases in the testis.

Neonatal testicular cell transplantation restores murine spermatogenesis damaged in the course of herpes simplex virus-induced orchitis

Genital tract infection and inflammation may affect male fertility, causing germ and Sertoli cell loss. We determined if testicular cell transplantation is effective at repairing testicular injury induced by herpes simplex virus (HSV) orchitis. ROSA26 mice were used as donors and the recipients were C57BL/6 mice after HSV testicular inoculation; some of the recipients were treated with the antiviral drug acyclovir (ACV). ACV reduced the amount of HSV antigen in testes on Day 3 after transplantation and enhanced the efficacy of transplantation at Day 30. In recipient testes, donor Sertoli cells formed new seminiferous tubules; significantly more new tubules were observed in the testes of ACV-treated mice compared with mice not treated with ACV (17.8% vs 3.6%). Over half (50.4%) of new tubules in ACV-treated testes contained germ cells and round spermatids were detected in 14.2% of new tubules compared with 15.9% and 5.3% in testes not treated with ACV, respectively. At Day 150 the seminiferous epithelium was completely recovered in some donor tubules and elongated spermatids were observed inside it. Thus, our findings reveal the effectiveness of the combination of antiviral therapy with neonatal testis-cell transplantation for the restoration of spermatogenesis damaged by viral infection.

Mono-(2-ethylhexyl) phthalate-induced Sertoli cell injury stimulates the production of pro-inflammatory cytokines in Fischer 344 rats

Exposure of rodents to the Sertoli cell (SC) toxicant mono-(2-ethylhexyl) phthalate (MEHP) has been reported to trigger an infiltration of macrophages into the testis in an age- and species-dependent manner. Here we challenge the hypothesis that the peripubertal rat-specific infiltration of macrophages after MEHP exposure is due, in part, to an increase in SC-specific inflammatory cytokine expression. To rule out that germ cell(GC) apoptosis itself is responsible for macrophage recruitment, rats were exposed to a direct GC toxicant, methoxyacetic acid (MAA), but no infiltration of macrophages was observed. Next, mRNA levels of inflammatory cytokines were evaluated after MEHP exposure. IL-1α, IL-6, and MCP-1 expression were increased in vivo and correlated with macrophage infiltration in a species-specific manner. Additionally, IL-6 and MCP-1 expression was increased in SC-GC co-cultures and ASC-17D SCs. These results indicate that MEHP-injury in pubertal rats specifically stimulates secretion of pro-inflammatory cytokines and alters the immune microenvironment.

Cytokines in Male Fertility and Reproductive Pathologies: Immunoregulation and Beyond

Germline development in vivo is dependent on the environment formed by somatic cells and the differentiation cues they provide; hence, the impact of local factors is highly relevant to the production of sperm. Knowledge of how somatic and germline cells interact is central to achieving biomedical goals relating to restoring, preserving or restricting fertility in humans. This review discusses the growing understanding of how cytokines contribute to testicular function and maintenance of male reproductive health, and to the pathologies associated with their abnormal activity in this organ. Here we consider both cytokines that signal through JAKs and are regulated by SOCS, and those utilizing other pathways, such as the MAP kinases and SMADs. The importance of cytokines in the establishment and maintenance of the testis as an immune-privilege site are described. Current research relating to the involvement of immune cells in testis development and disease is highlighted. This includes new data relating to testicular cancer which reinforce the understanding that tumorigenic cells shape their microenvironment through cytokine actions. Clinical implications in pathologies relating to local inflammation and to immunotherapies are discussed.

Transcriptome analysis of the responses to methyl methanesulfonate treatment in mouse pachytene spermatocytes and round spermatids

Spermatogenesis is threatened by DNA alkylating agents, one major category of DNA damaging agents. Currently, little is known about the alterations in transcriptome profiling of the mouse spermatogenic cells in response to DNA alkylation at distinct stages of spermatogenesis. In this study, RNA sequencing (RNA-seq) was performed in pachytene spermatocytes (PS) and round spermatids (RS) at 0 or 30min following Methyl Methanesulfonate (MMS) treatment and with untreated controls. A large number of differentially expressed genes (DEGs) were identified by comparison of the three groups in PS and RS, respectively. Functional analyses of all DEGs highlighted the protein ubiquitination pathway and DNA damage response (DDR) network being the two main biological processes in common in the two cell types. Further analyses of the DEGs with 2-fold or more changes between 30min repair and control group indicated that several cytokine signaling pathways were the most strongly affected in PS and DDR related pathways in RS, respectively. Gene ontology (GO) analyses directly showed differential biological process (BP) affected between PS and RS, with "regulation of transcription" being most overrepresented in PS and "cellular response to stress" in RS, respectively. Moreover, 374 DDR-related genes in PS and 158 in RS among all DEGs were filtered and clustered, which showed dynamic expression patterns in PS and RS. Our analyses provide a transcriptional landscape for male germ cells in response to MMS during spermatogenesis.

Regulation of blood-testis barrier by actin binding proteins and protein kinases

The blood-testis barrier (BTB) is an important ultrastructure in the testis, since the onset of meiosis and spermiogenesis coincides with the establishment of a functional barrier in rodents and humans. It is also noted that a delay in the assembly of a functional BTB following treatment of neonatal rats with drugs such as diethylstilbestrol or adjudin also delays the first wave of spermiation. While the BTB is one of the tightest blood-tissue barriers, it undergoes extensive remodeling, in particular, at stage VIII of the epithelial cycle to facilitate the transport of preleptotene spermatocytes connected in clones across the immunological barrier. Without this timely transport of preleptotene spermatocytes derived from type B spermatogonia, meiosis will be arrested, causing aspermatogenesis. Yet the biology and regulation of the BTB remains largely unexplored since the morphological studies in the 1970s. Recent studies, however, have shed new light on the biology of the BTB. Herein, we critically evaluate some of these findings, illustrating that the Sertoli cell BTB is regulated by actin-binding proteins (ABPs), likely supported by non-receptor protein kinases, to modulate the organization of actin microfilament bundles at the site. Furthermore, microtubule-based cytoskeleton is also working in concert with the actin-based cytoskeleton to confer BTB dynamics. This timely review provides an update on the unique biology and regulation of the BTB based on the latest findings in the field, focusing on the role of ABPs and non-receptor protein kinases.

Cytokines in the blood and semen of infertile patients

Cytokines have been important mediators of the immunity and can be involved in numerous processes in the male genital tract including acting as immunomodulatory elements within the male gonad.

The aims of this study were: 1) to detect pro- and anti-inflammatory cytokine levels in the control group and subgroups of infertile men; and 2) to set up the practical recommendations concerning determination of cytokine levels for the male infertility diagnosis.

Observations were performed in a group of 82 men: healthy controls (n = 27) and infertile patients (n = 55). The male infertility group was further subdivided into patients with: varicocele (n = 22), idiopathic infertility (n = 13) and partners of couples with recurrent spontaneous abortion (RSA; n = 20). Semen analysis was determined following WHO criteria. The cytokine interleukin 1β (IL-1β), IL-6, IL-10, IL-18; tumor necrosis factor α (TNF-α), interferon g (IFN-g) and transforming growth factor β1 (TGF-β1) contents in serum and seminal plasma were determined by quantitative ELISA.

An interesting marker of male infertility appears to be TGF-β1 (blood) significantly elevated in idiopathically infertile males and in the RSA group. Besides elevated TGF-β1 in a group of idiopathic infertility significantly elevated IL-10, IL-18, IFN-g (blood) and statistically decreased IL-1β while increased IFN-g were revealed in seminal plasma compared to healthy controls.

We may postulate novel cytokine micropatterns for patients with different background of infertility. Therefore, circulating cytokines: IL-1β, IL-10, IL-18, TGF-β1, IFN-g and IL-1β, IFN-g and TGF-β1 in seminal plasma should be extended in evaluation of specific types of male infertility.

The Mammalian Blood-Testis Barrier: Its Biology and Regulation

Spermatogenesis is the cellular process by which spermatogonia develop into mature spermatids within seminiferous tubules, the functional unit of the mammalian testis, under the structural and nutritional support of Sertoli cells and the precise regulation of endocrine factors. As germ cells develop, they traverse the seminiferous epithelium, a process that involves restructuring of Sertoli-germ cell junctions, as well as Sertoli-Sertoli cell junctions at the blood-testis barrier. The blood-testis barrier, one of the tightest tissue barriers in the mammalian body, divides the seminiferous epithelium into 2 compartments, basal and adluminal. The blood-testis barrier is different from most other tissue barriers in that it is not only comprised of tight junctions. Instead, tight junctions coexist and cofunction with ectoplasmic specializations, desmosomes, and gap junctions to create a unique microenvironment for the completion of meiosis and the subsequent development of spermatids into spermatozoa via spermiogenesis. Studies from the past decade or so have identified the key structural, scaffolding, and signaling proteins of the blood-testis barrier. More recent studies have defined the regulatory mechanisms that underlie blood-testis barrier function. We review here the biology and regulation of the mammalian blood-testis barrier and highlight research areas that should be expanded in future studies.

NC1 domain of collagen α3(IV) derived from the basement membrane regulates Sertoli cell blood-testis barrier dynamics

The blood-testis barrier (BTB) is an important ultrastructure for spermatogenesis. Delay in BTB formation in neonatal rats or its irreversible damage in adult rats leads to meiotic arrest and failure of spermatogonial differentiation beyond type A. While hormones, such as testosterone and FSH, are crucial to BTB function, little is known if there is a local regulatory mechanism in the seminiferous epithelium that modulates BTB function. Herein, we report that collagen α3(IV) chain, a component of the basement membrane in the rat testis, could generate a noncollagenous (NC1) domain peptide [Colα3(IV) NC1] via limited proteolysis by matrix metalloproteinase-9 (MMP-9), and that the expression of MMP-9 was upregulated by TNFα. While recombinant Colα3(IV) NC1 protein produced in E. coli failed to perturb Sertoli cell tight junction (TJ)-permeability barrier function, possibly due to the lack of glycosylation, Colα3(IV) NC1 recombinant protein produced in mammalian cells and purified to apparent homogeneity by affinity chromatography was found to reversibly perturb the Sertoli cell TJ-barrier function. Interestingly, Colα3(IV) NC1 recombinant protein did not perturb the steady-state levels of several TJ- (e.g., occludin, CAR, JAM-A, ZO-1) and basal ectoplasmic specialization- (e.g., N-cadherin, α-catenin, β-catenin) proteins at the BTB but induced changes in protein localization and/or distribution at the Sertoli cell-cell interface in which these proteins moved from the cell surface into the cell cytosol, thereby destabilizing the TJ function. These findings illustrate the presence of a local regulatory axis known as the BTB-basement membrane axis that regulates BTB restructuring during spermatogenesis.

Regulation of drug transporters in the testis by environmental toxicant cadmium, steroids and cytokines

The blood-testis barrier (BTB) provides an efficient barrier to restrict paracellular and transcellular transport of substances, such as toxicants and drugs, limiting their entry to the testis to cause injury. This is achieved by the coordinated actions of efflux and influx transporters at the BTB, which are integral membrane proteins that interact with their substrates, such as drugs and toxicants. An efflux transporter (e.g., P-glycoprotein) can either restrict the entry of drugs/toxicants into the testis or actively pump drugs/toxicants out of Sertoli and/or germ cells if they have entered the seminiferous epithelium via influx pumps. This thus provides an effective mechanism to safeguard spermatogenesis. Using Sertoli cells cultured in vitro with an established tight junction (TJ)-permeability barrier which mimicked the BTB in vivo and treated with cadmium chloride (CdCl2), and also in adult rats (~300 g b.w.) treated with CdCl2 (3 mg/kg b.w., via i.p.) to induce testicular injury, cadmium was found to significantly downregulate the expression of efflux (e.g., P-glycoprotein, Mrp1, Abcg1) and influx (e.g., Oatp3, Slc15a1, Scl39a8) transporters. For instance, treatment of Sertoli cells with cadmium induced significant loss of P-glycoprotein and Oatp-3 at the cell-cell interface, which likely facilitated cadmium entry into the Sertoli cell. These findings illustrate that one of the mechanisms by which cadmium enters the testis is mediated by downregulating the expression of drug transporters at the BTB. Furthermore, cytokines and steroids were found to have differential effects in regulating the expression of drug transporters. Summary, the expression of drug transporters in the testis is regulated by toxicants, steroids and cytokines.

Tumor necrosis factor α-mediated restructuring of the Sertoli cell barrier in vitro involves matrix metalloprotease 9 (MMP9), membrane-bound intercellular adhesion molecule-1 (ICAM-1) and the actin cytoskeleton

The mammalian blood-testis barrier (BTB) restructures throughout spermatogenesis, thereby allowing developing germ cells to enter the adluminal compartment of the seminiferous epithelium. Previous studies have shown pro-inflammatory cytokines such as tumor necrosis factor α (TNFα) and interleukin-1α to be important regulators of Sertoli cell barrier/BTB function in vitro and in vivo. In this study, the effects of TNFα on Sertoli cell barrier function were assessed, with emphasis on changes in proteases and cell adhesion molecules following treatment. By immunoblotting and immunohistochemistry, MMP9 was found to be present in germ cells, localizing by and large to spermatocytes and spermatids in the adult rat testis. Following treatment of Sertoli cells with physiologically relevant consecutive doses of recombinant human TNFα (25 ng/ml), the steady-state levels of active-matrix metalloprotease 9 (MMP9), membrane-bound intercellular adhesion molecule (mICAM-1) and androgen receptor increased significantly. TNFα also downregulated the steady-state level of occludin, in agreement with earlier results that showed TNFα to disrupt Sertoli cell barrier/BTB function. In addition, TNFα affected the filamentous actin cytoskeleton in Sertoli cells, which appeared to be mediated by cortactin, a regulator of actin dynamics. Taken collectively, these findings imply that germ cells may be involved in BTB restructuring via the localized production of TNFα. These results also illustrate that barrier restructuring correlated with an increase in Sertoli cell mICAM-1, suggesting that it may be critical for adhesion as germ cells traverse the “opened” BTB.

Age- and species-dependent infiltration of macrophages into the testis of rats and mice exposed to mono-(2-Ethylhexyl) phthalate (MEHP)

The mechanism by which noninfectious testicular inflammation results in infertility is poorly understood. Here the infiltration of CD11b+ immunoreactive testicular interstitial cells (neutrophil, macrophages, dendritic cells) in immature (Postnatal Day [PND] 21, 28, and 35) and adult (PND 56) Fischer rats is described at 12, 24, and 48 h after an oral dose of 1 g/kg mono-(2-ethylhexyl) phthalate (MEHP), a well-described Sertoli cell toxicant. Increases of CD11b+ cells are evident 12 h after MEHP exposure in PND 21 and 28 rats. In PND 28 rats, CD11b+ cells remained significantly elevated at 48 h, while in PND 21 rats, it returned to control levels by 24 h. The peak number of CD11b+ cells in PND 35 rat testis is delayed until 24 h, but remains significantly elevated at 48 h. In PND 56 rats, no increase in CD11b+ cells occurs after MEHP exposure. In PND 21, 28, and 35 rats, a significant increase in monocyte chemoattractant protein-1 (MCP-1) by peritubular myoid cells occurs 12 h after MEHP. Interestingly, MEHP treatment of C57BL/6J mice did not incite an infiltration of CD11b+ cells at either PND 21 or 28. The peak level of germ cell apoptosis observed 24 h after MEHP exposure in young rats is not seen in mice at any age or in PND 56 rats. Taken together, these findings implicate MCP-1 released by peritubular myoid cells in provoking the migration of CD11b+ cells into the immature rat testis early after MEHP exposure and point to a role for CD11b+ cells in triggering germ cell apoptosis in an age- and species-dependent manner.

Herpes simplex virus inoculation in murine rete testis results in irreversible testicular damage

This study aimed to establish the influence of herpes simplex virus (HSV) on testis morphology and germ cell development using a model of ascending urogenital HSV infection in mice. Adult C57BL/6J mice were inoculated with 100 plaque-forming units of HSV1 in rete testis. Viral proteins and HSV DNA were detected from 3 days postinoculation (DPI), while capsids and virions could be visualized at 6 DPI. Infectious activity of HSV was revealed by rapid culture method in testes from 3 to 14 DPI, and virus DNA by PCR - from 3 to 100 DPI. Germ and Sertoli cells were infected during the early stages of the infection, whereas interstitial cells only occasionally contained the virus at 21 and 45 DPI. Microscopic analysis revealed severe degeneration of the germinal epithelium in the infected testes. By 21 DPI, testes became atrophic and most Sertoli cells were destroyed. No testicular regeneration and no spermatozoa in the epididymis were observed at 45 and 100 DPI. From 3 DPI, inflammatory cells accumulated in the interstitium between damaged tubules; a significant increase in the number of CD4(+), CD8(+) T lymphocytes and F4/80(+) cells was observed in the infected testes. This study shows that in the case of HSV retrograde ascent into seminiferous tubules, the acute viral infection results in irreversible atrophy of the germinal epithelium, orchitis and infertility. These results may be used to further study viral orchitis and the influence of HSV on spermatogenesis and male fertility.

New insights into FAK function and regulation during spermatogenesis

Germ cell transport across the seminiferous epithelium during the epithelial cycle is crucial to spermatogenesis, although molecular mechanism(s) that regulate these events remain unknown. Studies have shown that spatiotemporal expression of crucial regulatory proteins during the epithelial cycle represents an efficient and physiologically important mechanism to regulate spermatogenesis without involving de novo synthesis of proteins and/or expression of genes. Herein, we critically review the role of focal adhesion kinase (FAK) in coordinating the transport of spermatids and preleptotene spermatocytes across the epithelium and the BTB, respectively, along the apical ectoplasmic specialization (ES) - blood-testis barrier - basement membrane (BM) functional axis during spermatogenesis. In the testis, p-FAK-Tyr&#179;&#8312;&#8311; and p-FAK-Tyr&#8308;&#8304;&#8311; are spatiotemporally expressed during the epithelial cycle at the actin-rich anchoring junction known as ES, regulating cell adhesion at the Sertoli-spermatid (apical ES) and Sertoli cell-cell (basal ES) interface. Phosphorylated forms of FAK exert their effects by regulating the homeostasis of F-actin at the ES, mediated via their effects on actin polymerization so that microfilaments are efficiently re-organized, such as from their "bundled" to "de-bundled/branched" configuration and vice versa during the epithelial cycle to facilitate the transport of: (i) spermatids across the epithelium, and (ii) preleptotene spermatocytes across the BTB. In summary, p-FAK-Tyr&#8308;&#8304;&#8311; and p-FAK-Tyr&#179;&#8312;&#8311; are important regulators of spermatogenesis which serve as molecular switches that turn "on" and "off" adhesion function at the apical ES and the basal ES/BTB, mediated via their spatiotemporal expression during the epithelial cycle. A hypothetical model depicting the role of these two molecular switches is also proposed.

The immune privilege of testis and gravid uterus: same difference?

The fetus in the gravid uterus and the developing spermatogenic cells in the adult testis both comprise special challenges for the host immune system. Protection of the neoantigens of the fetus and male germ cells from immune attack, defined as immune privilege, is fundamental for the propagation of species. Immune privilege is not simply the absence of leukocytes, but involves immune and non-immune cells acting synergistically together at multiple levels to create a unique tolerogenic environment. A number of the pathways are shared by the testis and gravid uterus. Amongst them steroid hormones, namely testosterone in the male and progesterone in the female, seem to function as key molecules that govern the local production of immunoregulatory factors which finally control the overall immune environment.

The effect of 17α-ethynylestradiol on steroidogenesis and gonadal cytokine gene expression is related to the reproductive stage in marine hermaphrodite fish

Pollutants have been reported to disrupt the endocrine system of marine animals, which may be exposed through contaminated seawater or through the food chain. Although 17α-ethynylestradiol (EE₂), a drug used in hormone therapies, is widely present in the aquatic environment, current knowledge on the sensitivity of marine fish to estrogenic pollutants is limited. We report the effect of the dietary intake of 5 µg EE₂/g food on different processes of testicular physiology, ranging from steroidogenesis to pathogen recognition, at both pre-spermatogenesis (pre-SG) and spermatogenesis (SG) reproductive stages, of gilthead seabream (Sparus aurata L.), a marine hermaphrodite teleost. A differential effect between pre-SG and SG specimens was detected in the sex steroid serum levels and in the expression profile of some steroidogenic-relevant molecules, vitellogenin, double sex- and mab3-related transcription factor 1 and some hormone receptors. Interestingly, EE₂ modified the expression pattern of some immune molecules involved in testicular physiology. These differences probably reflect a developmental adjustment of the sensitivity to EE₂ in the gilthead seabream gonad.

The role of endocannabinoids in gonadal function and fertility along the evolutionary axis

Endocannabinoids are natural lipids able to bind to cannabinoid and vanilloid receptors. Their biological actions at the central and peripheral level are under the tight control of the proteins responsible for their synthesis, transport and degradation. In the last few years, several reports have pointed out these lipid mediators as critical signals, together with sex hormones and cytokines, in various aspects of animal and human reproduction. The identification of anandamide (AEA) and 2-arachidonoylglycerol (2-AG) in reproductive cells and tissues of invertebrates, vertebrates and mammals highlights the key role played by these endogenous compounds along the evolutionary axis. Here, we review the main actions of endocannabinoids on female and male reproductive events, and discuss the interplay between them, steroid hormones and cytokines in regulating fertility. In addition, we discuss the involvement of endocannabinoid signalling in ensuring a correct chromatin remodeling, and hence a good DNA quality, in sperm cells.

The blood-testis barrier and its implications for male contraception

The blood-testis barrier (BTB) is one of the tightest blood-tissue barriers in the mammalian body. It divides the seminiferous epithelium into the basal and the apical (adluminal) compartments. Meiosis I and II, spermiogenesis, and spermiation all take place in a specialized microenvironment behind the BTB in the apical compartment, but spermatogonial renewal and differentiation and cell cycle progression up to the preleptotene spermatocyte stage take place outside of the BTB in the basal compartment of the epithelium. However, the BTB is not a static ultrastructure. Instead, it undergoes extensive restructuring during the seminiferous epithelial cycle of spermatogenesis at stage VIII to allow the transit of preleptotene spermatocytes at the BTB. Yet the immunological barrier conferred by the BTB cannot be compromised, even transiently, during the epithelial cycle to avoid the production of antibodies against meiotic and postmeiotic germ cells. Studies have demonstrated that some unlikely partners, namely adhesion protein complexes (e.g., occludin-ZO-1, N-cadherin-β-catenin, claudin-5-ZO-1), steroids (e.g., testosterone, estradiol-17β), nonreceptor protein kinases (e.g., focal adhesion kinase, c-Src, c-Yes), polarity proteins (e.g., PAR6, Cdc42, 14-3-3), endocytic vesicle proteins (e.g., clathrin, caveolin, dynamin 2), and actin regulatory proteins (e.g., Eps8, Arp2/3 complex), are working together, apparently under the overall influence of cytokines (e.g., transforming growth factor-β3, tumor necrosis factor-α, interleukin-1α). In short, a "new" BTB is created behind spermatocytes in transit while the "old" BTB above transiting cells undergoes timely degeneration, so that the immunological barrier can be maintained while spermatocytes are traversing the BTB. We also discuss recent findings regarding the molecular mechanisms by which environmental toxicants (e.g., cadmium, bisphenol A) induce testicular injury via their initial actions at the BTB to elicit subsequent damage to germ-cell adhesion, thereby leading to germ-cell loss, reduced sperm count, and male infertility or subfertility. Moreover, we also critically evaluate findings in the field regarding studies on drug transporters in the testis and discuss how these influx and efflux pumps regulate the entry of potential nonhormonal male contraceptives to the apical compartment to exert their effects. Collectively, these findings illustrate multiple potential targets are present at the BTB for innovative contraceptive development and for better delivery of drugs to alleviate toxicant-induced reproductive dysfunction in men.

Immunophysiology and pathology of inflammation in the testis and epididymis

The ability of spermatogenic cells to evade the host immune system and the ability of systemic inflammation to inhibit male reproductive function represent two of the most intriguing conundrums of male reproduction. Clearly, an understanding of the underlying immunology of the male reproductive tract is crucial to resolving these superficially incompatible observations. One important consideration must be the very different immunological environments of the testis, where sperm develop, and the epididymis, where sperm mature and are stored. Compared with the elaborate blood-testis barrier, the tight junctions of the epididymis are much less effective. Unlike the seminiferous epithelium, immune cells are commonly observed within the epithelium, and can even be found within the lumen, of the epididymis. Crucially, there is little evidence for extended allograft survival (immune privilege) in the epididymis, as it exists in the testis, and the epididymis is much more susceptible to loss of immune tolerance. Moreover, the incidence of epididymitis is considerably greater than that of orchitis in humans, and susceptibility to sperm antibody formation after damage to the epididymis or vas deferens increases with increasing distance of the damage from the testis. Although we still know relatively little about testicular immunity, we know less about the interactions between the epididymis and the immune system. Given that the epididymis appears to be more susceptible to inflammation and immune reactions than the testis, and thereby represents the weaker link in protecting developing sperm from the immune system, it is probably time this imbalance in knowledge was addressed.

Regulation of Sertoli cell activin A and inhibin B by tumour necrosis factor α and interleukin 1α: interaction with follicle-stimulating hormone/adenosine 3',5'-cyclic phosphate signalling

Regulation of crucial events during spermatogenesis involves dynamic changes in cytokine production and interactions across the cycle of the seminiferous epithelium. Regulation of activin A and inhibin B production by the inflammatory cytokines, tumour necrosis factor α (TNFα) and interleukin 1α (IL1α), alone and in conjunction with FSH or a cAMP analogue (dibutyryl cAMP), was examined in cultures of Sertoli cells from 20-day old rats. Both TNFα and IL1α stimulated activin A secretion and expression of its subunit (β(A)) mRNA, and suppressed inhibin B secretion and expression of its subunit (α and β(B)) mRNAs. The actions of TNFα and IL1α were opposed by FSH and dibutyryl cAMP. Both cytokines inhibited FSH/dibutyryl cAMP-stimulated inhibin B secretion and mRNA expression as well as stem cell factor mRNA expression. Both cytokines also inhibited FSH-induced cAMP production, and reduced baseline FSH receptor mRNA expression. These data highlight the reciprocal relationship that exists between FSH/cAMP signalling and inflammatory cytokine signalling pathways in the control of Sertoli cell function, and production of activin A/inhibin B in particular. It is anticipated that these interactions play important roles in the fine control of events during the cycle of the seminiferous epithelium and in the inhibition of spermatogenesis during inflammation.

Toll-like receptors and signalling in spermatogenesis and testicular responses to inflammation--a perspective

It is self-evident that infection and inflammation in the reproductive tract can inhibit male fertility, but the observation that fertility may also be compromised by systemic inflammation and disease is more difficult to explain. Recent studies implicating microbial pattern-recognition receptors, such as the Toll-like receptors (TLRs), as well as inflammatory cytokines and their signalling pathways, in testicular function have cast new light on this mysterious link between infection/inflammation and testicular dysfunction. It is increasingly evident that signalling pathways normally involved in controlling inflammation play fundamental roles in regulating Sertoli cell activity and responses to reproductive hormones, in addition to promoting immune responses within the testis. Many of the negative effects of inflammation on spermatogenesis may be attributed to elevated production of inflammation-related gene products within the circulation and the testis, which subsequently exert disruptive effects on spermatogenic cell development and survival, as well as the ability of the Sertoli cells to provide support for spermatogenesis. These interactions have important implications for testicular dysfunction and disease, and may eventually provide new opportunities for therapeutic interventions.

Regulation of spermatogenesis in the microenvironment of the seminiferous epithelium: new insights and advances

Spermatogenesis is a complex biochemical event, involving the participation of the hypothalamus and the pituitary gland via secretion of the hypothalamus hormone GnRH, and two pituitary hormones FSH and LH. Thus, the hypothalamic-pituitary-testicular axis is a crucial regulatory axis for testicular function. Recent studies have shown that in the microenvironment of the seminiferous epithelium, wherein each Sertoli cell supports approximately 30-50 germ cells at different stages of development, locally produced autocrine and paracrine factors are also involved in spermatogenesis, in particular at the level of cell junctions. These cell junctions at the Sertoli-Sertoli and Sertoli-germ cell interface are crucial for coordinating different events of spermatogenesis by sending signals back-and-forth between Sertoli and germ cells, in order to precisely regulate spermatogonial cell renewal by mitosis, cell cycle progression, meiosis, spermiogenesis, germ cell movement across the epithelium, spermiation and germ cell apoptosis. In this minireview, we provide an update on these latest findings for an emerging new concept regarding the presence of a local "apical ectoplasmic specialization-blood-testis barrier-hemidesmosome/basement membrane" functional axis that regulates the events of spermiation and blood-testis barrier (BTB) restructuring via paracrine/autocrine factors and polarity proteins produced locally in the seminiferous epithelium. These findings provide a new window of research for investigators in the field to tackle the functional regulation of spermatogenesis.

Immunology of the Testis and Male Reproductive Tract

A large body of evidence points to the existence of a close, dynamic relationship between the immune system and the male reproductive tract, which has important implications for our understanding of both systems. The testis and the male reproductive tract provide an environment that protects the otherwise highly immunogenic spermatogenic cells and sperm from immunological attack. At the same time, secretions of the testis, including androgens, influence the development and mature functions of the immune system. Activation of the immune system has negative effects on both androgen and sperm production, so that systemic or local infection and inflammation compromise male fertility. The mechanisms underlying these interactions have begun to receive the attention from reproductive biologists and immunologists that they deserve, but many crucial details remain to be uncovered. A complete picture of male reproductive tract function and its response to toxic agents is contingent upon continued exploration of these interactions and the mechanisms involved.

Immunoprivileged sites: the testis

The testis is an immunological privileged tissue as evidenced by its ability to support grafts with minimal rejection. Immune privilege is essential for the tolerance of neo-antigens from developing germ cells that appear after the constitution of self-tolerance, but imposes the paradoxical task of also providing efficient protection against pathogens and tumor cells. It is becoming increasingly clear that immune privilege cannot be attributed to a single factor such as the sequestration of neo-antigens from the immune system behind the blood-testis barrier, but is based on a complex multifaceted interplay between cells and factors that are essential for the reproductive function of the testis and the testicular immune system. This review summarizes the evidence that has accumulated regarding the role of Sertoli cells, androgens, and selected population of leukocytes in the maintenance of immune privilege and its perturbation in testicular inflammatory sub- and infertility.