Exploring the cyclooxygenase 2 (COX2)/15d-Δ(12,14)PGJ(2) system in hamster Sertoli cells: regulation by FSH/testosterone and relevance to glucose uptake

Impact of COVID-19 on sperm quality and the prostaglandin and polyamine systems in the seminal fluid

BACKGROUND

The implications of SARS-CoV-2 infection on male fertility remain largely unknown. Besides their well-known pro- and anti-inflammatory actions, prostaglandins and polyamines are present in semen, where they play key roles in sperm quality.

OBJECTIVES

To analyze semen parameters, oxidative profile and the seminal fluid prostaglandin and polyamine systems in samples collected from individuals without coronavirus disease 2019 diagnosis and men who recovered from coronavirus disease 2019.

MATERIALS AND METHODS

This study compared semen collected from men without positive coronavirus disease 2019 diagnosis with samples obtained from individuals 1-6 months and 7-30 months post SARS-CoV-2 infection. Semen parameters, thiobarbituric acid reactive substances, cyclooxygenase 2 expression by fluorescence immunocytochemistry and immunoblotting, prostaglandin levels by enzyme immunoassay, ornithine decarboxylase activity by a radioactive assay, and polyamine and acetylated polyamine levels by thin-layer chromatography were assessed.

RESULTS

In both groups of semen samples from coronavirus disease 2019 recovered men, sperm vitality, total and progressive sperm motility, and putrescine levels were significantly decreased when compared with samples from the uninfected group. In contrast, lipid peroxidation, leukocyte-associated cyclooxygenase 2 expression, and prostaglandin D2 levels were higher in semen from coronavirus disease 2019 recovered men than in samples from uninfected individuals. While sperm concentration and morphology, ornithine decarboxylase activity, and N-acetylputrescine levels were statistically diminished in semen obtained up to 6 months after coronavirus disease 2019 recovery, these parameters remained unchanged when samples were collected 7-30 months after coronavirus disease 2019 recovery. Coronavirus disease 2019 vaccination did not show negative effects on any of the parameters evaluated.

DISCUSSION AND CONCLUSION

Our work provides insights into the detrimental impact of coronavirus disease 2019 on several sperm parameters, in some cases, even more than a year after SARS-CoV-2 infection, which would be accompanied by alterations in the seminal fluid prostaglandin and polyamine profiles. Therefore, future treatments targeting the prostaglandin and polyamine pathways in coronavirus disease 2019 recovered men could lead to a successful reinstatement of semen parameters.

Melatonin improves oxidative state and lactate metabolism in rodent Sertoli cells

Antioxidant actions of melatonin and its impact on testicular function and fertility have already been described. Considering that Sertoli cells contribute to provide structural support and nutrition to germ cells, we evaluated the effect of melatonin on oxidative state and lactate metabolism in the immature murine TM4 cell line and in immature hamster Sertoli cells. A prooxidant stimulus applied to rodent Sertoli cells expressing MT1/MT2 receptors, increased lipid peroxidation whereas decreased antioxidant enzymes (superoxide dismutase 1, catalase, peroxiredoxin 1) expression and catalase activity. These changes were prevented by melatonin. Furthermore, melatonin stimulated lactate dehydrogenase (LDH) expression/activity via melatonin receptors, and increased intracellular lactate production in rodent Sertoli cells. Interestingly, oral melatonin supplementation in infertile men positively regulated LDHA testicular mRNA expression. Overall, our work provides insights into the potential benefits of melatonin on Sertoli cells contributing to testicular development and the future establishment of a sustainable spermatogenesis.

Pleiotropic actions of melatonin in testicular peritubular myoid cells of immature Syrian hamsters

BACKGROUND

Peritubular myoid cells are emerging as key regulators of testicular function in adulthood. However, little is known about the role of testicular peritubular myoid cells (TPMCs) in the development of the male gonad. We found that, compared to testes of young adult hamsters, gonads of 21 day-old animals show increased melatonin concentration, seminiferous tubular wall thickening and a heterogeneous packaging of its collagen fibers thus raising the question whether melatonin may be involved in the regulation of TPMCs.

METHODS

We established primary cultures of TPMCs from immature hamsters (ihaTPMCs), which we found express melatonergic receptors.

RESULTS

Exogeneous melatonin decreased the levels of inflammatory markers (NLRP3 inflammasome, IL1β) but increased the expression of cyclooxygenase 2 (COX2, key enzyme mediating prostaglandin synthesis) and of the glial cell line-derived neurotrophic factor (GDNF) in ihaTPMCs. Melatonin also stimulated ihaTPMCs proliferation and the expression of extracellular matrix proteins such as collagen type I and IV. Furthermore, collagen gel contraction assays revealed an enhanced ability of ihaTPMCs to contract in the presence of melatonin.

CONCLUSION

Melatonin regulates immune and inflammatory functions as well as contractile phenotype of the peritubular wall in the hamster testis.

GENERAL SIGNIFICANCE

If transferable to the in vivo situation, melatonin-dependent induction of ihaTPMCs to produce factors known to exert paracrine effects in other somatic cell populations of the gonad suggests that the influence of melatonin may go beyond the peritubular wall and indicates its contribution to testicular development and the establishment of a normal and sustainable spermatogenesis.

Cigarette heavy smoking alters DNA methylation patterns and gene transcription levels in humans spermatozoa

Tobacco smoking is considered the most common reason of death and infertility around the world. This study was designed to assess the impact of tobacco heavy smoking on sperm DNA methylation patterns and to determine whether the transcription level of ALDH3B2, PTGIR, PRICKLE2, and ALS2CR12 genes is different in heavy smokers compared to non-smokers. As a screening study, the 450 K array was used to assess the alteration in DNA methylation patterns between heavy smokers (n = 15) and non-smokers (n = 15). Then, four CpGs that have the highest difference in methylation level (cg16338278, cg08408433, cg05799088, and cg07227024) were selected for validation using deep bisulfite sequencing in an independent cohort of heavy smokers (n = 200) and non-smokers (n = 100). A significant variation was found between heavy smokers and non-smokers in the methylation level at all CpGs within the PRICKLE2 and ALS2CR12 gene amplicon (P < 0.001). Similarly, a significant variation was found in the methylation level at nine out of thirteen CpGs within the ALDH3B2 gene amplicon (P < 0.01). Additionally, eighteen CpGs out of the twenty-six within the PTGIR gene amplicon have a significant difference in the methylation level between heavy smokers and non-smokers (P < 0.01). The study showed a significant difference in sperm global DNA methylation, chromatin non-condensation, and DNA fragmentation (P < 0.001) between heavy smokers and non-smokers. A significant decline was shown in the transcription level of ALDH3B2, PTGIR, PRICKLE2, and ALS2CR12 genes (P < 0.001) in heavy smokers. In conclusion, heavy smoking influences DNA methylation at several CpGs, sperm global DNA methylation, and transcription level of the PRICKLE2, ALS2CR12, ALDH3B2, and PTGIR genes, which affects negatively the semen parameters of heavy smokers.

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

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

What Does Androgen Receptor Signaling Pathway in Sertoli Cells During Normal Spermatogenesis Tell Us?

Androgen receptor signaling pathway is necessary to complete spermatogenesis in testes. Difference between androgen binding location in Sertoli cell classifies androgen receptor signaling pathway into classical signaling pathway and non-classical signaling pathway. As the only somatic cell type in seminiferous tubule, Sertoli cells are under androgen receptor signaling pathway regulation via androgen receptor located in cytoplasm and plasma membrane. Androgen receptor signaling pathway is able to regulate biological processes in Sertoli cells as well as germ cells surrounded between Sertoli cells. Our review will summarize the major discoveries of androgen receptor signaling pathway in Sertoli cells and the paracrine action on germ cells. Androgen receptor signaling pathway regulates Sertoli cell proliferation and maturation, as well as maintain the integrity of blood-testis barrier formed between Sertoli cells. Also, Spermatogonia stem cells achieve a balance between self-renewal and differentiation under androgen receptor signaling regulation. Meiotic and post-meiotic processes including Sertoli cell - Spermatid attachment and Spermatid development are guaranteed by androgen receptor signaling until the final sperm release. This review also includes one disease related to androgen receptor signaling dysfunction named as androgen insensitivity syndrome. As a step further ahead, this review may be conducive to develop therapies which can cure impaired androgen receptor signaling in Sertoli cells.

Male and female gonadal ageing: its impact on health span and life span

Ageing is linked to changes in the hypothalamic-pituitary-gonadal axis and a progressive decline in gonadal function. While women become infertile when they enter menopause, fertility decline in ageing men does not necessarily involve a complete cessation of spermatogenesis. Gonadal dysfunction in elderly people is characterized by morphological, endocrine and metabolic alterations affecting the reproductive function and quality of life. With advancing age, sexuality turns into a critical emotional and physical factor actually defining the number of years that ageing people live a healthy life. Gonadal ageing correlates with comorbidities and an increased risk of age-related diseases including diabetes, kidney problems, cardiovascular failures and cancer. This article briefly summarizes the current state of knowledge on ovarian and testicular senescence, explores the experimental models used in the study of gonadal ageing, and describes the local pro-inflammatory, oxidative and apoptotic events and the associated signalling pathways that take place in the gonads while people get older. Overall, literature reports that ageing exacerbates a mutual crosstalk among oxidative stress, apoptosis and the inflammatory response in the gonads leading to detrimental effects on fertility. Data also highlight the clinical implications of novel therapeutic interventions using antioxidant, anti-apoptotic and anti-inflammatory drugs on health span and life span.

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

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

Multiple signaling pathways in Sertoli cells: recent findings in spermatogenesis

The functions of Sertoli cells in spermatogenesis have attracted much more attention recently. Normal spermatogenesis depends on Sertoli cells, mainly due to their influence on nutrient supply, maintenance of cell junctions, and support for germ cells' mitosis and meiosis. Accumulating evidence in the past decade has highlighted the dominant functions of the MAPK, AMPK, and TGF-β/Smad signaling pathways during spermatogenesis. Among these pathways, the MAPK signaling pathway regulates dynamics of tight junctions and adherens junctions, proliferation and meiosis of germ cells, proliferation and lactate production of Sertoli cells; the AMPK and the TGF-β/Smad signaling pathways both affect dynamics of tight junctions and adherens junctions, as well as the proliferation of Sertoli cells. The AMPK signaling pathway also regulates lactate supply. These signaling pathways combine to form a complex regulatory network for spermatogenesis. In testicular tumors or infertile patients, the activities of these signaling pathways in Sertoli cells are abnormal. Clarifying the mechanisms of signaling pathways in Sertoli cells on spermatogenesis provides new insights into the physiological functions of Sertoli cells in male reproduction, and also serves as a pre-requisite to identify potential therapeutic targets in abnormal spermatogenesis including testicular tumor and male infertility.

Expression of PTGS2, PGFS and PTGFR during downregulation and restart of spermatogenesis following GnRH agonist treatment in the dog

Prostaglandins (PGs) and prostaglandin endoperoxide synthase (PTGS) are considered to be relevant for spermatogenesis and steroidogenesis. PTGS2, prostaglandin F synthase (PGFS) and PGF receptor (PTGFR) are investigated in the adult male dog using the model of the GnRH-agonist implant downregulated canine testis and its subsequent restart of spermatogenesis following abolition of treatment (3, 6, 9, 12 weeks after implant removal). On the mRNA level (ratio), PTGS2, PGFS and PTGFR expression did not differ between downregulation, different stages of recovery of spermatogenesis and untreated adult controls (CG). On the protein level, Sertoli and Leydig cells in all samples and some peritubular cells stained immunopositive for PTGS2. In the tubular compartment, the percentage of the PTGS2-immunopositive area (PIA) and the mean PTGS2-staining intensity (gray scale, GS) did not differ between groups but in the interstitial compartment, the PIA (p = 0.0494) and the GS (p < 0.0001) were significantly upregulated during early recrudescence (week 3/6). Comparing downregulation by two GnRH-agonist implants with juvenile controls (JG) and CG, the mRNA expression (ratio) did not differ. In the tubular compartment, the GS (p = 0.0321) was significantly higher at downregulation compared to CG and in the interstitial compartment, the PIA (p = 0.0073) and the GS (p = 0.0097) were significantly higher in JG compared to downregulation/CG. PTGS2, PGFS and PTGFR mRNA and PTGS2 protein are regularly expressed in the adult, juvenile and downregulated canine testis and downregulation and subsequent recrudescence affect PTGS2 protein expression mainly in Leydig cells. PTGS2 expression in the downregulated testis resembles the one in seasonal Syrian hamster but not juvenile canine testis.

Reactive oxygen species (ROS) production triggered by prostaglandin D2 (PGD2) regulates lactate dehydrogenase (LDH) expression/activity in TM4 Sertoli cells

Reactive oxygen species (ROS) regulate testicular function in health and disease. We previously described a prostaglandin D2 (PGD2) system in Sertoli cells. Now, we found that PGD2 increases ROS and hydrogen peroxide (H2O2) generation in murine TM4 Sertoli cells, and also induces antioxidant enzymes expression suggesting that defense systems are triggered as an adaptive stress mechanism that guarantees cell survival. ROS and specially H2O2 may act as second messengers regulating signal transduction pathways and gene expression. We describe a stimulatory effect of PGD2 on lactate dehydrogenase (LDH) expression via DP1/DP2 receptors, which is prevented by the antioxidant N-acetyl-L-cysteine and the PI3K/Akt pathway inhibitor LY 294002. PGD2 also enhances Akt and CREB/ATF-1 phosphorylation. Our results provide evidence for a role of PGD2 in the regulation of the oxidant/antioxidant status in Sertoli cells and, more importantly, in the modulation of LDH expression which takes place through ROS generation and the Akt-CREB/ATF-1 pathway.

Peripheral and Central Mechanisms Involved in the Hormonal Control of Male and Female Reproduction

Reproduction involves the integration of hormonal signals acting across multiple systems to generate a synchronised physiological output. A critical component of reproduction is the luteinising hormone (LH) surge, which is mediated by oestradiol (E2 ) and neuroprogesterone interacting to stimulate kisspeptin release in the rostral periventricular nucleus of the third ventricle in rats. Recent evidence indicates the involvement of both classical and membrane E2 and progesterone signalling in this pathway. A metabolite of gonadotrophin-releasing hormone (GnRH), GnRH-(1-5), has been shown to stimulate GnRH expression and secretion, and has a role in the regulation of lordosis. Additionally, gonadotrophin release-inhibitory hormone (GnIH) projects to and influences the activity of GnRH neurones in birds. Stress-induced changes in GnIH have been shown to alter breeding behaviour in birds, demonstrating another mechanism for the molecular control of reproduction. Peripherally, paracrine and autocrine actions within the gonad have been suggested as therapeutic targets for infertility in both males and females. Dysfunction of testicular prostaglandin synthesis is a possible cause of idiopathic male infertility. Indeed, local production of melatonin and corticotrophin-releasing hormone could influence spermatogenesis via immune pathways in the gonad. In females, vascular endothelial growth factor A has been implicated in an angiogenic process that mediates development of the corpus luteum and thus fertility via the Notch signalling pathway. Age-induced decreases in fertility involve ovarian kisspeptin and its regulation of ovarian sympathetic innervation. Finally, morphological changes in the arcuate nucleus of the hypothalamus influence female sexual receptivity in rats. The processes mediating these morphological changes have been shown to involve the rapid effects of E2 controlling synaptogenesis in this hypothalamic nucleus. In summary, this review highlights new research in these areas, focusing on recent findings concerning the molecular mechanisms involved in the central and peripheral hormonal control of reproduction.

Seminal cyclooxygenase relationship with oxidative stress in infertile oligoasthenoteratozoospermic men with varicocele

This study aimed to assess the relation of seminal cyclooxygenase COX-1, COX-2 with oxidative stress in infertile oligoasthenoteratozoospermic (OAT) men with varicocele (Vx). In all, 128 men were allocated into fertile men, fertile men with Vx, infertile OAT men without Vx and infertile OAT men with Vx. They were subjected to history taking, clinical examination and semen analysis. Also, seminal COX-1, COX-2, malondialdehyde (MDA) and glutathione peroxidase (GPx) were estimated. Mean levels of seminal COX-1, COX-2 were over-expressed, the mean level of seminal MDA was significantly increased, and the mean level of seminal GPx was significantly decreased in infertile OAT men with Vx compared with other groups. Seminal COX-1 and COX-2 were over-expressed in cases with Vx grade III compared with Vx grades I, II cases and in cases with bilateral Vx compared with unilateral Vx. There was significant negative correlation between seminal COX-1 and COX-2 with sperm concentration, sperm motility, sperm normal morphology, seminal GPx and significant positive correlation with seminal MDA. It is concluded that seminal COX-1 and COX-2 are over-expressed in infertile OAT men with Vx compared with fertile men with/without and infertile OAT men without Vx being associated with oxidative stress, Vx grade and Vx laterality.

Cyclooxygenase and prostaglandins in somatic cell populations of the testis

Prostaglandins (PGs) are synthesized through the action of the rate-limiting enzyme cyclooxygenase (COX) and further specific enzymes. The development ofCox-deficient mice in the 1990s gave insights into the reproductive roles of PGs. FemaleCox-knockout mice were subfertile or infertile. Interestingly, fertility was not affected in male mice deficient inCox, suggesting that PGs may not be critical for the functioning of the testis. However, this conclusion has recently been challenged by observations of important roles for PGs in both physiological and pathological processes in the testis. The two key somatic cell types in the testis, Leydig and Sertoli cells, express the inducible isoenzyme COX2 and produce PGs. Testicular COX2 expression in these somatic cells is regulated by hormonal input (FSH, prolactin (PRL), and testosterone) as well as by IL1β. PGs modulate steroidogenesis in Leydig cells and glucose uptake in Sertoli cells. Hence, the COX2/PG system in Leydig and Sertoli cells acts as a local modulator of testicular activity, and consequently may regulate spermatogenic efficiency. In addition to its expression in Leydig and Sertoli cells, COX2 has been detected in the seminiferous tubule wall, and in testicular macrophages and mast cells of infertile patients. These observations highlight the possible relevance of PGs in testicular inflammation associated with idiopathic infertility. Collectively, these data indicate that the COX2/PG system plays crucial roles not only in testicular physiology (i.e., development, steroidogenesis, and spermatogenesis), but more importantly in the pathogenesis or maintenance of infertility status in the male gonad. Further studies of these actions could lead to new therapeutic approaches to idiopathic male infertility.

Free German abstract

A German translation of this abstract is freely available athttp://www.reproduction-online.org/content/149/4/R169/suppl/DC1.

Free Spanish abstract

A Spanish translation of this abstract is freely available athttp://www.reproduction-online.org/content/149/4/R169/suppl/DC2.

Melatonin in testes of infertile men: evidence for anti-proliferative and anti-oxidant effects on local macrophage and mast cell populations

Melatonin acting through the hypothalamus and pituitary regulates testicular function. In addition, direct actions of melatonin at the testicular level have been recently suggested. We have described that melatonin inhibits androgen production in hamster Leydig cells via melatonin subtype 1a (mel1a) receptors and the local corticotrophin-releasing hormone (CRH) system. The initial events of the melatonin/CRH signalling pathway have also been established. Melatonin and all components of the melatonergic/CRH system were also detected in Leydig cells of infertile men. This study attempted to search for additional targets of melatonin in the human testis, and to investigate the effects of melatonin on proliferation and the oxidative state in these novel target cells. To this aim, evaluation of human testicular biopsies of patients suffering from hypospermatogenesis or Sertoli cell only syndrome and cell culture studies were performed. Melatonergic receptors were found in macrophages (MACs) and mast cells (MCs) of the human testis. In biopsies of patients suffering idiopathic infertility, melatonin testicular concentrations were negatively correlated with MAC number per mm(2) and TNFα, IL1β and COX2 expression, but positively correlated with the expression of the anti-oxidant enzymes SOD1, peroxiredoxin 1 and catalase. Melatonin inhibited proliferation and the expression of pro-inflammatory cytokines and cyclooxygenase 2 (COX2) in both the human non-testicular THP-1 MAC cell line and primary cell cultures of hamster testicular MACs. In the human HMC-1 MC line, melatonin increased the expression of anti-oxidant enzymes and decreased reactive oxygen species (ROS) generation. The results reveal new testicular targets of melatonin and describe anti-proliferative and anti-inflammatory effects of this hormone on testicular MACs. Furthermore, melatonin might provide protective effects against oxidative stress in testicular MCs.