Differential effects of dexamethasone treatment on lipopolysaccharide-induced testicular inflammation and reproductive hormone inhibition in adult rats

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

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

Astaxanthin ameliorates the impairment consequence of prenatal bacterial lipopolysaccharide exposure in adult male offspring NMRI mice

In this study, the potential effects of astaxanthin (AST) were investigated on preventing the prenatal LPS-induced injures in mothers and adult male offspring of NMRI mice. Pregnant mice were randomly divided into four groups: 1. Saline + vehicle; 2. Saline + AST: received astaxanthin (4 mg/kg for 3 days, ip) on 11-13 gestation days; 3. LPS + vehicle (LPS-treated group): injected with LPS (20 µg/kg, sc) on gestation day 11; 4. LPS + AST: administrated LPS and astaxanthin on gestation days 11 and 11-13, respectively. In each group, maternal care behaviors and TNF-α serum levels were examined until weaning of male offspring at 23 days. At 60 days old, male pups underwent analysis of body weight and length, serum gonadotropins and testosterone hormone levels, sperm quality, gonadal and brain tissues morphologies, and the expression of SOX9 and GnRH genes by real-time PCR. Serum TNF-α level increased significantly in mothers treated with LPS, while AST reduced it. In adult male offspring, serum hormone levels, sperm quality, and the number of spermatocytes and Leydig cells in the testes improved when AST was administrated. According to histological studies of the brain, neurons in the LPS-treated group were smaller and less active, whereas neurons in the LPS + AST group were larger, more numerous, and more active. LPS significantly reduced GnRH expression, while AST induction improved its expression. AST administration during pregnancy prevented the adverse effects of prenatal exposure to LPS, presumably through its genomic and non-genomic effects, in adult male offspring.

BPA disrupts the SC barrier integrity by activating the cytokines/JNK signaling pathway in rare minnow Gobiocypris rarus

Bisphenol-A (BPA) has been reported to disrupt blood-testis barrier (BTB) integrity in mammals. However, its effects on fish testis sertoli cell (SC) barrier and the underlying mechanisms have been largely unknown to date. To study the SC barrier toxicity induced by BPA, male rare minnows (Gobiocypris rarus) were exposed to 15 μg L ^- 1 BPA for 7, 14 and 21 d. Meanwhile, a 25 ng L^-1 17α-ethynyl estradiol (EE2) group was set up as the positive control. Results showed that BPA induced immune response in the testes and decreased offspring hatching rate. The biotin tracer assay showed that BPA exposure destroyed the integrity of the testis SC barrier. In addition, BPA exposure decreased the expressions of occludin, ZO-1, CX43 and N-cadherin proteins. The transcripts of CX43 and occludin were significantly decreased and SP1 recruitment in each gene promoter was repressed after BPA exposure. Moreover, the cytokines (TNFα and IL-1β) were significantly increased while the JNK signal pathway was activated after BPA exposure. BPA also increased the matrix metalloproteinases 1 (MMP1) and MMP2 levels in the testes. In addition, estrogenic effect did not entirely explain the mechanism by which BPA disrupted the SC barrier in G. rarus testes. These results suggested that BPA disrupted the SC barrier integrity by inhibiting SP1 enrichments within CX43 and occludin 5' flanking regions through activated cytokines/JNK signaling pathway. MMPs were also involved in the disruption of SC barrier caused by BPA exposure.

Oxidative Stress, Testicular Inflammatory Pathways, and Male Reproduction

Inflammation is among the core causatives of male infertility. Despite male infertility being a serious global issue, "bits and pieces" of its complex etiopathology still remain missing. During inflammation, levels of proinflammatory mediators in the male reproductive tract are greater than usual. According to epidemiological research, in numerous cases of male infertility, patients suffer from acute or chronic inflammation of the genitourinary tract which typically occurs without symptoms. Inflammatory responses in the male genital system are inextricably linked to oxidative stress (OS). OS is detrimental to male fertility parameters as it causes oxidative damage to reproductive cells and intracellular components. Multifarious male infertility causative factors pave the way for impairing male reproductive functions via the common mechanisms of OS and inflammation, both of which are interlinked pathophysiological processes, and the occurrence of any one of them induces the other. Both processes may be simultaneously found in the pathogenesis of male infertility. Thus, the present article aims to explain the role of inflammation and OS in male infertility in detail, as well as to show the mechanistic pathways that link causative factors of male reproductive tract inflammation, OS induction, and oxidant-sensitive cellular cascades leading to male infertility.

Chronic exposure to Bisphenol A resulted in alterations of reproductive functions via immune defense, oxidative damage and disruption DNA/histone methylation in male rare minnow Gobiocypris rarus

Bisphenol A (BPA) is a widely used chemical that represents a reproductive hazard in fish. However, the molecular pathways mediating reproductive toxicity under chronic BPA exposure remain unclear. To study the reproductive hazards associated with chronic BPA exposure, adult male rare minnows (Gobiocypris rarus) were treated with 15 μg L ^- 1 and 225 μg L ^- 1 BPA for 90 days. Results showed that chronic BPA treatment induced reproductive impairments with decreased fertilization capacity and movement time of sperm. Transcriptome analysis indicated 1421 transcripts that were differentially expressed in response to BPA exposure, which are involved in the biological process of oxidative stress, immune responses and DNA/histone methylation. BPA caused the oxidative stress via significantly increasing hydrogen peroxide (H₂O₂) levels and inhibiting the activities of antioxidant-related enzymes (Catalase, CAT). BPA caused an inflammatory response in the testes by significantly increasing IL-1β levels and inducing infiltration of inflammatory cells. Moreover, exposure to 15 μg L ^- 1 BPA significantly decreased the genomic DNA methylation level. These data revealed that chronic BPA exposure had adverse effects on male reproduction. Oxidative stress, inflammatory response and DNA/histone methylation might account for the decreased sperm quality.

Low testicular zinc level, p53 expression and impairment of Sertoli cell phagocytosis of residual bodies in rat subjected to psychological stress

Psychological stress is a known aetiology of infertility. However, the mechanisms translating it to reproductive dysfunction are not fully elucidated. Three experiments were performed on Wistar rats were designed to evaluate Sertoli cell function under stress. In Experiment I, rats were randomised into three groups: saline baseline group given saline, ASEMA baseline group given aqueous extract of Massularia acuminata, zinc baseline group administered zinc orally. In Experiment II, exposure to psychological stress (for 1 hour per day) was layered on Experiment I while Experiment III substituted stress with administration of dexamethasone (DX). Six rats were sacrificed per group per experiment on days 7 and 14 and the right testis was excised and processed for PAS-haematoxylin staining and the left used for Zn determination. Results show significantly lower testicular Zn level as well more intensely immunoexpression of p53 in saline stress and saline DX groups compared with other groups. Also seen are the presence of residual bodies in the seminiferous tubular lumen of saline groups in Experiments II and III suggesting failure of residual bodies to be transported back towards the basement membrane. This study demonstrates that psychological stress impairs the ability of Sertoli cells to recycle residual bodies.

Effects of bacteria on male fertility: Spermatogenesis and sperm function

Bacterial infection can negatively affect different parts of the male genital tract and subsequently cause impaired spermatogenesis and male fertility. However, most of the previous studies have focused on the infected organs of the male genital tract and there are not many studies that investigated the direct effect of bacteria on sperm and their mechanism of action. Interestingly, bacteria can induce different damages on sperm cells such as DNA fragmentation, cell membrane peroxidation, and acrosome impairment. Such negative effects can be mediated by bacteria-secreted toxins and metabolites or by direct attachment of bacteria on the sperm cells and subsequent activation of signaling pathways related to oxidative stress, apoptosis, and inflammation. These bacteria-induced changes can impair semen parameters and subsequently cause infertility. Given the significant destructive effect of some bacteria on sperm function and male fertility, in this study, we reviewed the impact of male urogenital bacteria on spermatogenesis and sperm functions as well as the underlying mechanisms by which the bacteria can damage sperm.

LPS-induced alterations in reproductive organs and liver pigmentation in the toad Rhinella diptycha (Bufonidae)

Anurans can be naturally infected by the bacterium Escherichia coli (Migula, 1895) Castellani and Chalmers, 1919, which contain lipopolysaccharides (LPS) in their external membrane. LPS affects reproductive functions in mammals and extracutaneous pigmentary system of anurans. Besides the functional gonad, bufonid amphibians have an undeveloped female organ (Bidder’s organ), whose function is poorly known. We aimed to investigate the effects of LPS on testis and Bidder’s organ germ cells and on liver pigmentation in the toad Rhinella diptycha (Cope, 1862). Animals were inoculated with 0.1 mL of saline solution (control) or LPS solution (18 mg/kg) and then euthanized after 24 or 48 h. The organs were processed for histology and then evaluated with morphometric analysis. The LPS decreased the area of bundle spermatozoa and increased lumen spermatozoa, while in Bidder’s organ, the number of degenerating oocytes decreased. Liver melanin increased after 24 h and decreased after 48 h. Our results suggest that LPS delays the release of spermatozoa, possibly due to alterations in serum levels of testosterone and (or) gonadotropins, which may also explain fewer degrading cells in Bidder’s organ. Increased melanin in the liver was expected due to the bactericidal role of this pigment. Thus, LPS affected reproductive organs and induced cytoprotective responses in the liver of amphibians.

Infectious, inflammatory and 'autoimmune' male factor infertility: how do rodent models inform clinical practice?

BACKGROUND

Infection and inflammation of the reproductive tract are significant causes of male factor infertility. Ascending infections caused by sexually transmitted bacteria or urinary tract pathogens represent the most frequent aetiology of epididymo-orchitis, but viral, haematogenous dissemination is also a contributory factor. Limitations in adequate diagnosis and therapy reflect an obvious need for further understanding of human epididymal and testicular immunopathologies and their contribution to infertility. A major obstacle for advancing our knowledge is the limited access to suitable tissue samples. Similarly, the key events in the inflammatory or autoimmune pathologies affecting human male fertility are poorly amenable to close examination. Moreover, the disease processes generally have occurred long before the patient attends the clinic for fertility assessment. In this regard, data obtained from experimental animal models and respective comparative analyses have shown promise to overcome these restrictions in humans.

OBJECTIVE AND RATIONALE

This narrative review will focus on male fertility disturbances caused by infection and inflammation, and the usefulness of the most frequently applied animal models to study these conditions.

SEARCH METHODS

An extensive search in Medline database was performed without restrictions until January 2018 using the following search terms: 'infection' and/or 'inflammation' and 'testis' and/or 'epididymis', 'infection' and/or 'inflammation' and 'male genital tract', 'male infertility', 'orchitis', 'epididymitis', 'experimental autoimmune' and 'orchitis' or 'epididymitis' or 'epididymo-orchitis', antisperm antibodies', 'vasectomy'. In addition to that, reference lists of primary and review articles were reviewed for additional publications independently by each author. Selected articles were verified by each two separate authors and discrepancies discussed within the team.

OUTCOMES

There is clear evidence that models mimicking testicular and/or epididymal inflammation and infection have been instructive in a better understanding of the mechanisms of disease initiation and progression. In this regard, rodent models of acute bacterial epididymitis best reflect the clinical situation in terms of mimicking the infection pathway, pathogens selected and the damage, such as fibrotic transformation, observed. Similarly, animal models of acute testicular and epididymal inflammation using lipopolysaccharides show impairment of reproduction, endocrine function and histological tissue architecture, also seen in men. Autoimmune responses can be studied in models of experimental autoimmune orchitis (EAO) and vasectomy. In particular, the early stages of EAO development showing inflammatory responses in the form of peritubular lymphocytic infiltrates, thickening of the lamina propria of affected tubules, production of autoantibodies against testicular antigens or secretion of pro-inflammatory mediators, replicate observations in testicular sperm extraction samples of patients with 'mixed atrophy' of spermatogenesis. Vasectomy, in the form of sperm antibodies and chronic inflammation, can also be studied in animal models, providing valuable insights into the human response.

WIDER IMPLICATIONS

This is the first comprehensive review of rodent models of both infectious and autoimmune disease of testis/epididymis, and their clinical implications, i.e. their importance in understanding male infertility related to infectious and non-infectious/autoimmune disease of the reproductive organs.

Human sperm Toll-like receptor 4 (TLR4) mediates acrosome reaction, oxidative stress markers, and sperm parameters in response to bacterial lipopolysaccharide in infertile men

PURPOSE

To study the role of Toll-like receptor 4 (TLR4) in human spermatozoa and to assess sperm parameters, oxidative stress markers, and acrosome reaction in response to the stimulation of TLR4 by its ligand, the lipopolysaccharide (LPS), as a major endotoxin of Gram-negative bacteria.

METHODS

Our study was carried out in 73 sperm samples from patients undergoing semen analysis for couple infertility investigations. The studied patients were divided into three groups: normozoospermic fertile patients (n = 13), patients with abnormal and leukospermic semen (n = 13), and patients with abnormal and non-leukospermic semen (n = 47). TLR4 expression in human spermatozoa was initially analyzed by western blot. Sperm samples were incubated in the presence of LPS (200 ng/ml) for 18 h. Then, sperm motility and vitality were evaluated by microscopic observation and oxidative stress markers as malondialdehyde (MDA) and carbonyl groups (CG) were spectrophotometrically assessed in neat and selected sperm. A triple-stain technique was also performed to evaluate acrosome reaction in 15 sperm samples from infertile patients.

RESULTS

TLR4 expression was confirmed in human spermatozoa with a molecular weight of 69 kDa. In the normozoospermic group, no significant differences in sperm parameters and oxidative stress markers were shown after incubation with LPS in neat and selected sperms. Regarding samples from the non-leukospermic group, LPS reduced spermatozoa motility and vitality rates in selected sperm (P = 0.003; P = 0.004, respectively). A significant increase of MDA and CG levels was also detected (P = 0.01; P = 0.02, respectively). However, only the MDA levels were significantly increased (P = 0.01) in neat LPS-stimulated sperm. The same results were shown within the leukospermic group. The comparison between the two groups, leukospermic and non-leukospermic, in selected sperms showed a more important LPS effect in the leukospermic group significantly on motility and MDA rates (P = 0.006; P = 0.009, respectively). Furthermore, a significant decrease in reacted spermatozoa rate was detected in response to LPS in selected sperm samples from infertile men (P = 0.03).

CONCLUSIONS

These findings indicate that human spermatozoa express TLR4 and respond to LPS stimulation with alterations in viability, motility, and the acrosome reaction implicating reactive oxygen species (ROS) production in sperm samples from infertile patients.

Immunosuppressants and Male Reproduction

Prolonged use of immunosuppressant medications is occasionally seen in infertile men with chronic inflammatory conditions; autoimmune disorders; or an organ or hematopoietic stem cell transplant. Chronic inflammation impacts negatively on male reproductive endpoints, so immunosuppressant therapy can produce improvements. Corticosteroids have been used to treat antisperm antibodies and even as an empirical treatment for male infertility in general. Trials of these methods have provided mixed results on semen quality and fertility, with improvement, no change and negative effects reported by different investigators. In a substantial number of observational studies, patients on long-term therapy with prednisone for chronic inflammatory disease, testosterone levels were lower compared to untreated controls, though randomized controlled trials have not been conducted. Similarly decreases in testosterone have been reported in men receiving corticosteroids to minimize transplant rejection; however, most were treated with multiple immunosuppressive medications that may have contributed to this effect. A large number of trials of healthy men treated with corticosteroids have shown some disruption in reproductive hormone levels, but other studies reported no effect. Studies in monkeys, rats (at human equivalent dose), cattle, sheep, and horses have shown endocrine disruption, including low testosterone with dexamethasone treatment. Of the cytostatic immunosuppressives, which have high potential for cellular damage, cyclophosphamide has received the most attention, sometimes lowering sperm counts significantly. Methotrexate may decrease sperm numbers in humans and has significant negative impacts in rodents. Other chemotherapeutic drugs used as immunosuppressants are likely to impact negatively on male fertility endpoints, but few data have been collected. The TNF-α Inhibitors have also received little experimental attention. There is some evidence that the immunophilin modulators: cyclosporine, sirolimus, and everolimus cause endocrine disruption and semen quality impairment. As we review in this chapter, results in experimental species are concerning, and well-designed studies are lacking for the effects of these medications on reproductive endpoints in men.

Maternal LPS exposure during pregnancy impairs testicular development, steroidogenesis and spermatogenesis in male offspring

Lipopolysaccharide (LPS) is associated with adverse developmental outcomes including embryonic resorption, fetal death, congenital teratogenesis and fetal growth retardation. Here, we explored the effects of maternal LPS exposure during pregnancy on testicular development, steroidogenesis and spermatogenesis in male offspring. The pregnant mice were intraperitoneally injected with LPS (50 µg/kg) daily from gestational day (GD) 13 to GD 17. At fetal period, a significant decrease in body weight and abnormal Leydig cell aggregations were observed in males whose mothers were exposed to LPS during pregnancy. At postnatal day (PND) 26, anogenital distance (AGD), a sensitive index of altered androgen action, was markedly reduced in male pups whose mothers were exposed to LPS daily from GD13 to GD 17. At PND35, the weight of testes, prostates and seminal vesicles, and serum testosterone (T) level were significantly decreased in LPS-treated male pups. At adulthood, the number of sperm was significantly decreased in male offspring whose mothers were exposed to LPS on GD 13-17. Maternal LPS exposure during gestation obviously diminished the percent of seminiferous tubules in stages I-VI, increased the percent of seminiferous tubules in stages IX-XII, and caused massive sloughing of germ cells in seminiferous tubules in mouse testes. Moreover, maternal LPS exposure significantly reduced serum T level in male mice whose mothers were exposed to LPS challenge during pregnancy. Taken together, these results suggest that maternal LPS exposure during pregnancy disrupts T production. The decreased T synthesis might be associated with LPS-induced impairments for spermatogenesis in male offspring.

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.

Antimicrobial responses in the male reproductive tract of lipopolysaccharide challenged rats

PROBLEM

Innate immune machinery including the Toll-like receptors (TLRs) confers the first line of defense mechanisms to counter pathogenic microorganisms that enter the body. The male reproductive tract is vulnerable to infection and the role of TLRs and the antimicrobial responses that operate to counter infections in this organ system are poorly understood.

METHOD OF STUDY

Caput and cauda epididymides, testes and seminal vesicles were collected at 0, 3, 6, 9, 12, 15 and 24 h from rats injected intraperitoneally with a single dose of LPS. Plasma testosterone was measured using ELISA. Expression pattern of defensins and Spag11 isoforms were analysed using RT-PCR. Immunohistochemical analyses was performed to determine SPAG11E protein expression following LPS treatment.

RESULTS

We provide the first line of evidence that the male reproductive tract induces the expression of Sperm Associated Antigen 11 (Spag11) mRNA variants and defensins when challenged with lipopolysaccharide (LPS) with a concomitant increase in protein expression. However, there was an inverse relationship between induction of antimicrobial gene expression and plasma testosterone. An increase in the mRNA levels of proinflammatory cytokines was observed parallel to the induction of Spag11 variants and majority of defensin expression in the male reproductive tract.

CONCLUSION

The increase in Spag11 and defensin mRNA in response to LPS administration demonstrates their importance in protecting the male reproductive tract during infection. Results of this study help to understand male reproductive tract innate immune defense mechanisms and to design novel peptide antibiotics to prevent sexually transmitted diseases.

Neonatal lipopolysaccharide exposure attenuates the homotypic stress-induced suppression of LH secretion in adulthood in male rat

Neonatal immune challenges have a long-lasting influence on immune response. Using male Sprague-Dawley rats, we examined whether neonatal lipopolysaccharide (LPS) challenge alters the sensitivity of male reproductive function to adult LPS challenge and at which level (central or testes) the alteration occurs. We also examined the mRNA expression of proinflammatory cytokines in the hypothalamus and testes because they have a pivotal role in immune stress-induced suppression of gonadotropin secretion and testosterone synthesis. On day 10 after birth, all the pups were injected with LPS (100 microg/kg, i.p.) or saline. Thereafter, LPS (100 microg/kg, i.p.) or saline was injected in adulthood at 8 weeks of age. The serum LH concentration was decreased by LPS injection during adulthood in the neonatal saline-injected rats. This suppressive effect was not seen in the neonatal LPS-injected rats. The serum testosterone concentration was decreased by adult LPS injection in both the neonatal LPS-injected and neonatal saline-injected rats. The expression levels of KiSS-1, which encodes kisspeptin, known to have a crucial role in the regulation of gonadotropin secretion, and GnRH mRNA in the hypothalamus and LHbeta mRNA in the pituitary were not influenced by neonatal or adult LPS injection. On the other hand, the expression levels of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) mRNA in the hypothalamus and testes were increased by adult LPS injection in both the neonatal LPS-injected and neonatal saline-injected rats. Furthermore, the expression levels of these factors in the hypothalamus after adult LPS injection were significantly lower in the neonatal LPS-injected rats than in the neonatal saline-injected rats. These findings indicate that neonatal LPS challenge reduces the sensitivity of male reproductive function to the suppressive effects of LPS, mainly at the central level. Attenuation of proinflammatory cytokine synthesis in the hypothalamus might be involved in this alteration.

Immune response to bacteria in seminiferous epithelium

The luminal part of the seminiferous epithelium, a tissue compartment protected by the blood-testis barrier, has been considered a site of immune privilege. However, there are reports describing the production of anti-microbial peptides and the expression of Toll-like receptors in cells present in the seminiferous epithelium, evoking the possibility that this tissue compartment is immunologically active at least with regard to the innate immune response. To test this, we injected Escherichia coli into seminiferous tubules of live mice and examined the fate of bacteria, the production of chemokines and inflammatory cytokines, and the infiltration of neutrophils. The bacteria actively propagated and reached a maximal level in a day, but started to decrease after 5 days and completely disappeared in 2 months. The expression of macrophage inflammatory protein-2 and tumor necrosis factor-alpha became evident in macrophages present in the interstitial compartment of testes as early as 1-3 h after the inoculation of bacteria. Neutrophils first accumulated in the interstitial space at 9-12 h and entered the tubules after a day. On the other hand, impairment of spermatogenesis was observed a day after bacteria injection and seemed unrecoverable even after the bacteria were eliminated. By contrast, bacteria injected into the interstitial compartment were more rapidly cleared with no damage in the seminiferous epithelium. These results suggest the existence of immunity against invading microbes in the seminiferous epithelium although its effectiveness in maintaining tissue homeostasis remains equivocal.

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

Spermatogenesis is a complex, organized process involving intimate interactions between the developing germ cells and supporting Sertoli cells. The process is also highly regulated. Studies suggest that regulation in the seminiferous epithelium involves molecules normally associated with either immune or inflammatory processes; in particular, interleukin 1a (IL1a), IL6, tumor necrosis factor (TNFa), activin A and nitric oxide (NO). While there is considerable evidence that these inflammatory mediators have effects on spermatogonial and spermatocyte development as well as critical supportive functions of the Sertoli cells, which are undoubtedly of considerable importance during testicular inflammation, there remains some skepticism regarding the significance of these molecules with respect to normal testicular function. Nonetheless, it is evident that expression of these regulators varies across the cycle of the seminiferous epithelium in a consistent manner, with major changes in production coinciding with key events within the cycle. This review summarizes the evidence supporting the hypothesis that inflammatory cytokines play a role in normal testicular spermatogenesis, as well as in the etiology of inflammation induced sub-fertility. The balance of data leads to the striking conclusion that the cycle of the seminiferous epithelium resembles a chronic inflammatory event. This appears to be a somewhat paradoxical assertion, since the testis is an immunologically privileged tissue based on its well-established ability to support grafts with minimal rejection responses. However, it may be argued that local immunoregulatory mechanisms, which confer protection from immunity on both transplanted tissues and the developing spermatogenic cells, are equally necessary to prevent local inflammation responses associated with the spermatogenic process from activating the adaptive immune response.

Innervation and serotoninergic receptors of the testis interact with local action of interleukin-1beta on steroidogenesis

Testosterone secretion by Leydig cells is affected by interleukin-1beta (IL-1beta). The aim of the present study was to investigate whether partial denervation of the testis or local administration of a serotonin (5-HT) receptor antagonist could alter the changes in testicular steoidogenesis induced by IL-1beta. Intratesticular administration of IL-1beta was combined with vasectomy or local injection of ketanserin (5-HT type 2 receptor antagonist) in immature hemicastrated rats and the effect of the interventions on testicular steroidogenesis was studied. One day after treatment with local injection of IL-1beta induced a significant rise in testosterone secretion that could be prevented by vasectomy (that also means transection of the inferior spermatic nerve). In a model in which neither IL-1beta nor ketanserin interfered with steroidogenesis, administration of the receptor antagonist just prior to IL-1beta treatment significantly reduced testosterone secretion. Data indicate interaction between testicular nerves and IL-1beta action and interaction between testicular 5-HT2 receptors and local effect of IL-1beta on testosterone secretion.

Bacterial lipopolysaccharide-induced oxidative stress in the impairment of steroidogenesis and spermatogenesis in rats

Microbial infections, localized as well as systemic, are known to cause transitive or permanent male infertility. However, the mechanisms of infection-induced infertility are largely unknown. Earlier reports showed that steroidogenesis and spermatogenesis are affected during bacterial lipopolysaccharide (LPS)-induced acute inflammation. The present study used an LPS rat model to investigate the role of oxidative stress in spermatogenesis. Intraperitoneal administration of bacterial LPS (5mg/kg body weight) to adult male albino rats elevated testicular malondialdehyde (MDA) and 4-hydroxy-2-nonenal (HNE), and decreased the activities of testicular antioxidant enzymes such as catalase, superoxide dismutase, glutathione peroxidase, and glutathione reductase. The GSH/GSSG ratio also decreased significantly. Time series analysis revealed transitory oxidative stress and expression of inflammatory mediators such as interleukin-1beta (IL-1beta), inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2) from 3h to 12h after LPS. Testicular expression of steroidogenic acute regulatory (StAR) protein decreased to 24h, in correlation with damage to spermatogenesis. These data are consistent with oxidative stress as a major causal factor in altered steroidogenesis, spermatogenesis, and perhaps male infertility during endotoxin-induced acute inflammation.

Increased expression of interleukin-1α and interleukin-1β is associated with experimental varicocele

OBJECTIVE

To describe the effect of varicocele, in an experimental rat model, on the levels of IL-1alpha and IL-1beta proteins in testis tissue.

DESIGN

Comparative and controlled study.

SETTING

Experimental research.

ANIMAL(S)

Wistar male rats in experimental and control groups.

INTERVENTION(S)

The control group underwent sham operation (n = 6). Experimental groups underwent partial ligation of the renal vein to induce experimental varicocele and were then killed at 9 (n = 6), 11 (n = 6), and 13 (n = 6) weeks after induction of varicocele.

MAIN OUTCOME MEASURE(S)

Histologic evaluation of the varicocele model was determined by periodic acid-Schiff staining of paraffin-embeded testicular tissues. Levels of cytokines were assessed by immunohistochemistry and Western blot analysis.

RESULT(S)

Varicocele caused testicular damage, especially in 11- and 13-week-old varicocele groups. In sham-operated rats, Golgi complexes of round spermatids expressed especially the alpha form of IL-1. By the progression of varicocele, the IL-1alpha expression increased temporally in Sertoli cells, spermatogonia, primary spermatocytes, spermatids, and Leydig cells. The expression of IL-1beta was seen in Leydig cells in sham-operated rats. The IL-1beta expression was also increased upon progression of varicocele in Leydig cells, Sertoli cells, and spermatogonia.

CONCLUSION(S)

We suggest that IL-1alpha and IL-1beta are the regulators of testicular function. Certain pathologic conditions, e.g., varicocele, cause an increase in the expressions of such proinflammatory cytokines. The increased expression of IL-1alpha and IL-1beta in varicocele shifts the balance in favor of inflammatory and immune responses and causes detrimental effects in testis tissue, which may cause male infertility.

Maintenance of gonadotropin secretion by glucocorticoids under stress conditions through the inhibition of prostaglandin synthesis in the brain

We have previously reported that glucocorticoids counteract the suppressive effects of tumor necrosis factor-alpha on both pulsatile and surge secretion of LH. This suggests that glucocorticoids have a protective effect on reproductive function under infectious stress. In the present study, we examined whether glucocorticoids maintain pulsatile LH secretion under various conditions of acute stress and the possible involvement of prostaglandins (PGs) in glucocorticoid actions. Three different types of stressors, namely infectious (lipopolysaccharide, 0.5 microg/kg), hypoglycemic (2-deoxy-D-glucose, 100 mg/kg), and restraint stress (1 h) were applied to ovariectomized rats. In ovariectomized rats, LH pulses were partially suppressed by restraint, but not by lipopolysaccharide or 2-deoxy-D-glucose. On the other hand, adrenalectomy (ADX) significantly enhanced the suppressive effects of all the stressors applied on LH pulses. Treatment with both corticosterone (25 mg/kg) and indomethacin (10 mg/kg) in ADX rats significantly attenuated the suppressive effects of these stressors on LH pulses. In addition, the immunoreactivity of cyclooxygenase-2, a PG-synthesizing enzyme, in the brain under stress conditions was much enhanced by ADX, and this was counteracted by corticosterone treatment. Similarly, an increase in body temperature under restraint stress was enhanced by ADX and suppressed by corticosterone. These results suggest that suppression of LH pulsatility by stress is mediated by PGs in the brain, and that increased release of endogenous glucocorticoids in response to stress counteracts this suppression by inhibiting PG synthesis, and thereby maintains reproductive function regardless of the nature of the stressor.

Rapid modulation of TRH and TRH-like peptide levels in rat brain and peripheral tissues by corticosterone

Disturbance of glucocorticoid signaling has been implicated in several neuropsychiatric disorders including unipolar and bipolar depression and anxiety induced by maternal deprivation. Antidepressants have been shown to be neuroprotective and able to reverse damage to glia and neurons. Thyrotropin-releasing hormone (TRH) is an endogenous antidepressant that reduces the expression of glycogen synthase kinase-3beta (GSK-3beta), an enzyme that hyperphosphorylates tau and is implicated in bipolar depression, diabetes and Alzheimer's disease. In order to understand the potential role of TRH and TRH-like peptides both as mediators of the depressogenic effects of glucocorticoids and as potential therapeutics for neuropsychiatric disease, 300 g male Sprague-Dawley rats were injected i.p. with 4 mg corticosterone/0.5 ml 50% DMSO+50% ethanol and sacrificed 0, 2, 4 and 8h later. Levels of TRH and TRH-like peptides were measured in various brain regions involved in mood regulation and pancreas and reproductive tissues that mediate the metabolic and reproductive impairments associated with high glucocorticoid levels. Significant increases, ranging from 2- to 12-fold, in TRH or TRH-like peptide levels were observed in almost all brain regions studied at 4h after corticosterone injection. In cerebellum, TRH and TRH-like peptides increased 4-14-fold by 8h. TRH-like peptide levels fell 86-98% at 4h after treatment in testis. TRH, derived only from Leydig cells, was not affected. TRH and TRH-like peptides increased 2-4-fold at 8h in pancreas. TRH and TRH-like peptide concentrations in prostate were not affected by corticosterone up to 8h after injection. The 4h needed to detect a highly significant change in the TRH and TRH-like peptide levels in brain and peripheral tissues is consistent with the mediation of most corticosterone-effects via alterations in gene transcription.

Interleukin 1-beta injected into the testis acutely stimulates and later attenuates testicular steroidogenesis of the immature rat

The effect of intratesticular administration of interleukin-1beta (IL-1beta) on steroidogenesis was studied in immature and adult rats. In 21-d-old animals local bilateral injection or unilateral administration of 0.1 microg/testis of IL-1beta to hemicastrates resulted in a significant increase in basal testosterone secretion in vitro and serum testosterone concentration one day posttreatment. Six days after treatment the cytokine induced opposite effect in animals with two testes in situ, i.e., it suppressed steroidogenesis. When IL-1beta was combined with hemi-castration, IL-1beta failed to alter the parameters studied. In adult animals subjected to bilateral treatment or to unilateral injection followed by hemicastration, IL-1beta in doses of 1.5 microg/testis or 15 microg/testis did not influence steroidogenesis and serum testosterone concentration. No change in serum LH and FSH concentration could be observed in any experimental group. The data suggest that the proinflammatory cytokine IL-1beta exerts a local action on testicular steroidogenesis, and the effect is age-dependent.

Cytokine profiles in the testes of rats treated with lipopolysaccharide reveal localized suppression of inflammatory responses

Evidence indicates that the testis possesses a reduced capacity to mount inflammatory and rejection responses, which undoubtedly contributes to the ongoing survival of the highly immunogenic germ cells. The contribution of local cytokine expression to this condition was investigated in adult male rats treated with lipopolysaccharide to induce inflammation. Cytokine mRNA and protein expression were determined in tissue extracts and fluids by Northern blot analysis, quantitative PCR, or RNAse protection assay and specific ELISAs. Testicular expression of the proinflammatory cytokines, interleukin (IL)-1β and tumor necrosis factor-α was considerably attenuated compared with the liver (control tissue); in contrast, the testicular IL-6 response was enhanced. Expression of IL-10, a type 2 immunoregulatory cytokine, was similar in both testis and liver, whereas the immunoregulatory/anti-inflammatory cytokines transforming growth factor-β1and activin A were constitutively elevated in both normal and inflamed testes. The IL-1β and transforming growth factor-β1proteins were present principally in their latent (inactive) forms, indicating that enzymic processing is an important control mechanism for these two cytokines within the testis. These data indicate that inflammatory and regulatory cytokine activity is regulated at both transcriptional and posttranslational levels in a testis-specific manner. It is concluded that a novel pattern of suppression of proinflammatory cytokine responses and normal or elevated expression of immunoregulatory cytokines may be responsible for reduced inflammatory responses and enhanced graft survival in the testis. These data have important implications for the understanding and treatment of male autoimmune infertility, testicular inflammation. and carcinogenesis.

Elevated serum C-reactive protein in mumps orchitis

A case of mumps orchitis with a high concentration of C-reactive protein (CRP) prompted us to evaluate the inflammatory response in mumps complications. We compared the CRP titers in mumps patients with orchitis and meningitis. The serum CRP titers were significantly higher in the patients with orchitis than in those with meningitis.

Intratesticular delivery of tumor necrosis factor-alpha and ceramide directly abrogates steroidogenic acute regulatory protein expression and Leydig cell steroidogenesis in adult rats

Systemic or intratesticular release of TNF alpha and IL1 beta have been implicated in the reduced testosterone biosynthesis and impaired production of competent spermatozoa found in human patients suffering from sepsis or chronic inflammation. Although in vitro and in vivo studies have demonstrated that TNF alpha and IL1 beta intercept the hypothalamic-pituitary testis axis at different levels, the site(s) of action and relative contribution of each cytokine to the overall testicular failure associated to systemic inflammatory processes remains poorly defined. In this study we show that intratesticular delivery of TNF alpha induced a rapid (4 h) and sustained (up to 24 h) reduction in steroidogenic acute regulatory (StAR) protein expression and testosterone biosynthesis in nonstimulated or human chorionic gonadotropin-treated intact or hypophysectomized rats. Bilateral treatment with cell-permeant short-chain ceramides (C2-cer or C6-cer) reproduced the early (4 h) inhibitory action of TNFalpha on testosterone biosynthesis and testicular StAR expression. The inhibitory action of C2-cer or C6-cer was not observed in animals treated with inactive analogs (dihydroceramide), phosphorylcholine, sphingosine, or sphingosine-1P. In sharp contrast to the previously described ability of IL1 beta to prevent human chorionic gonadotropin-stimulated Leydig cell steroidogenesis in vitro, serum testosterone and testicular StAR protein expression remained unchanged in animals bilaterally injected with this cytokine. These data support the concept that TNF alpha triggers different effector mechanisms to directly inhibit Leydig cell StAR expression and steroidogenesis, which ultimately contribute to the global reproductive failure associated with chronic inflammation and sepsis.

Endotoxin inhibition of luteinizing hormone in sheep

Administration of endotoxin suppresses circulating concentration of luteinizing hormone (LH) in a number of species, including rats, sheep, cattle, and non-human primates. Specifically, endotoxin administration decreases circulating concentration of LH and LH pulses frequency in castrated male sheep. Endotoxin could alter circulating concentrations of LH via actions at the hypothalamus through altered GnRH production and/or release, or endotoxin could alter circulating concentrations of LH at the level of the pituitary via inhibition of LH production and release or inhibition of LH in response to GnRH. The site of endotoxin suppression of circulating concentrations of LH as well as possible mediators of endotoxin suppression of circulating concentrations of LH, including cortiocotropin-releasing hormone, arginine vasopressin, glucocorticoids, inflammatory cytokines, prostaglandins, and opioids, are discussed.

Corticosteroids are unable to protect against pseudorabies virus-induced tissue damage in the developing brain

After intraocular injection of the virulent pseudorabies virus (PRV) strain Becker into late-stage chicken embryos, the virus spreads and replicates in the brain, where severe edema and hemorrhaging follow. By contrast, the attenuated Bartha strain does not cause severe brain pathology despite viral replication and spread throughout the brain (B. W. Banfield, G. S. Yap, A. C. Knapp, and L. W. Enquist, J. Virol. 72:4580-4588, 1998). These observations prompted us to explore the mechanism by which the virulent Becker strain mediates pathology in the chicken embryo central nervous system (CNS). To test the hypothesis that Becker infection induced an inflammatory response in the developing CNS, we examined the ability of the anti-inflammatory corticosteroid dexamethasone (Dex) to protect chicken embryos from PRV-induced brain damage. We found that Dex is not sufficient to protect the chicken embryo CNS from damage due to Becker infection. Surprisingly, systemic Dex delivery appeared to potentiate CNS damage, which was preceded by petechial hemorrhaging in the optic lobes. Taken together, these data suggest that the severe pathology elicited during the Becker infection is due not to immunopathology but to damage by the virus itself, possibly through the damage to or destruction of endothelial cells.

Cytokines and the immune-testicular axis

Cytokines are regulatory proteins involved in haematopoiesis, immune cell development, inflammation and immune responses. Several cytokines have direct effects on testicular cell functions, and a number of these are produced within the testis even in the absence of inflammation or immune activation events. There is compelling evidence that cytokines, in fact, play an important regulatory role in the development and normal function of the testis. Pro-inflammatory cytokines including interleukin-1 and interleukin-6 have direct effects on spermatogenic cell differentiation and testicular steroidogenesis. Stem cell factor and leukaemia inhibitory factor, cytokines normally involved in haematopoiesis, also play a role in spermatogenesis. Anti-inflammatory cytokines of the transforming growth factor-beta family are implicated in testicular development. Consequently, local or systemic up-regulation of cytokine expression during injury, illness or infection may contribute to the disruption of testicular function and fertility that frequently accompanies these conditions. The aim of this review is to provide a very brief summary of the extensive literature dealing with cytokines in testicular biology, and to follow this with some speculation concerning the significance of these molecules in interactions between the immune system and the testis.

Macrophages and the immune responsiveness of the testis

Immune responses within the testis are regulated in a manner that provides protection for the developing male germ cells, while permitting qualitatively normal inflammatory responses and protection against infection. The large population of resident-type macrophages in the testis is strongly implicated in mediating this specialised immunological environment. Several studies in the rat have shown that testicular macrophages retain their cytotoxic and phagocytic capacity, but have greatly diminished pro-inflammatory function and even exhibit immunosuppressive activity. While the local mechanisms that control the phenotype of the testicular macrophage population are unknown, evidence points to the influence of the testicular somatic cells, the Sertoli and Leydig cells. A smaller but significant population of macrophages that lack expression of resident macrophage markers, is also found in the rat testis. The functional role of these macrophages remains to be defined, but they most likely represent circulating monocytes or newly-arrived testicular macrophages, and, therefore, may contribute to sustaining inflammatory responses within the testis. Further investigation of the immune-related functions of these different macrophage subsets, and the testicular somatic cells, during immunological and inflammatory events should provide a better understanding of how the testicular immune environment is maintained and regulated.

Murine tumor necrosis factor-alpha sensitizes plasma corticosterone activity and the manifestation of shock: modulation by histamine

Murine tumor necrosis factor-alpha (mTNF-alpha) results in the sensitization of mechanisms underlying plasma corticosterone activity and sickness behavior, the latter being reminiscent of septic or anaphylactic shock. The mTNF-alpha induced a sensitization of sickness and corticosterone in mice that was attenuated by pretreatment with the combinations of histamine H(1) (diphenhydramine, mepyramine) and H(2) (cimetidine) antagonists. Likewise, coadministration of diphenhydramine and cimetidine prevented the mTNF-alpha-provoked rise of monoamine activity within the posterior hypothalamus. Although dexamethasone ameliorated the mTNF-alpha-induced sensitization of corticosterone, illness behavior was unaffected. It is suggested that mTNF-alpha-induced illness and the neuroendocrine sensitization are mediated by endogenous histamine.

Increase in serum level of interleukin-1 alpha mediates morphine anti-inflammatory effect in carrageenan-induced paw oedema in mice

In the present studies we examined the effects of an intra-peritoneal injection of morphine (7 mg/kg) on carrageenan-induced paw oedema in mice. Carrageenan-induced paw oedema was measured by mercury plethysmometer and was maximal at hour 3, and pretreatment with morphine could reduce the oedema significantly. At the same time the serum levels of interleukin-1 alpha (IL-1 alpha) were increased. Pretreatment with naloxone and dexamethasone abolished morphine anti-inflammatory while decreasing IL-1 alpha serum levels, significantly. These findings suggest that an increase in serum levels of IL-1 alpha plays an important role in the anti-inflammatory effect of morphine.