Involvement of serum and lipopolysaccharide in the production of interleukin-1- and interleukin-6-like molecules by human sperm cells

Gut Endotoxin Leading to a Decline IN Gonadal function (GELDING) - a novel theory for the development of late onset hypogonadism in obese men

Obesity is an increasing public health problem, with two-thirds of the adult population in many Western countries now being either overweight or obese. Male obesity is associated with late onset hypogonadism, a condition characterised by decreased serum testosterone, sperm quality plus diminished fertility and quality of life. In this paper we propose a novel theory underlying the development of obesity related hypogonadism- the GELDING theory (Gut Endotoxin Leading to a Decline IN Gonadal function). Several observational studies have previously reported an association between obesity related hypogonadism (low testosterone) and systemic inflammation. However, for the first time we postulate that the trans-mucosal passage of bacterial lipopolysaccharide (LPS) from the gut lumen into the circulation is a key inflammatory trigger underlying male hypogonadism. Obesity and a high fat/high calorie diet are both reported to result in changes to gut bacteria and intestinal wall permeability, leading to the passage of bacterial endotoxin (lipopolysaccharide- LPS) from within the gut lumen into the circulation (metabolic endotoxaemia), where it initiates systemic inflammation. Endotoxin is known to reduce testosterone production by the testis, both by direct inhibition of Leydig cell steroidogenic pathways and indirectly by reducing pituitary LH drive, thereby also leading to a decline in sperm production. In this paper we also highlight the novel evolutionary benefits of the GELDING theory. Testosterone is known to be a powerful immune-suppressive, decreasing a man's ability to fight infection. Therefore we postulate that the male reproductive axis has evolved the capacity to lower testosterone production during times of infection and resulting endotoxin exposure, decreasing the immunosuppressive influence of testosterone, in turn enhancing the ability to fight infection. While this response is adaptive in times of sepsis, it becomes maladaptive in the setting of "non-infectious" obesity related metabolic endotoxaemia.

Distinct expression of interleukin-1α, interleukin-1β, and interleukin-1 receptor antagonist in testicular tissues and cells from human biopsies with normal and abnormal histology

Cytokines are paracrine/autocrine growth factors known to affect testicular cell functions. The cellular origin and expression levels of interleukin-1 (IL-1) in human normal and pathological testicular biopsies are not yet clear. In the present study, we have investigated the levels and cellular origin of IL-1 family members [IL-1α, IL-β, and IL-1 receptor antagonist (IL-1ra)] in human testicular normal and abnormal biopsies with incomplete maturation arrest (IMA) or Sertoli only syndrome (SOS), using real-time polymerase chain reaction and immunohistochemical staining analysis. Our results show that the levels of IL-1α were higher in Leydig/interstitial cells of biopsies with IMA and SOS compared with normal. The levels of IL-1α in Sertoli cells of normal biopsies were higher than IMA and SOS. The mRNA levels of IL-1α were similar in all biopsies. IL-1β levels were higher in Leydig/interstitial cells of normal biopsies compared with Sertoli and germ cells. The levels of IL-1β were similar in testicular cells of all biopsies. However, the mRNA levels of IL-1β were significantly lower in SOS and IMA biopsies compared with normal. IL-1ra was expressed only in Leydig/interstitial cells, and their expression in normal biopsies was higher than in biopsies with IMA and SOS. The mRNA levels of IL-1ra were similar in all biopsies. Thus, it is possible to suggest the involvement of IL-1 system in the regulation of spermatogenesis and male infertility.

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.

Effect of interleukin-1 receptor antagonist gene deletion on male mouse fertility

Members of the IL-1 family are pleiotropic cytokines that are involved in inflammation, immunoregulation, and other homeostatic functions in the body. IL-1alpha, IL-1beta, and the IL-1 antagonistic molecule [IL-1 receptor antagonist (IL-1 Ra)] are present in the testis under normal homeostasis, and they further increase upon infection/inflammation. In the present study, we examined the effect of IL-1 Ra gene deletion on male mouse fertility. Male mice [wild type (WT) and IL-1 Ra knockout (KO)] were mated with WT females, and the birth and number of offspring were recorded 21-45 d after mating. Furthermore, the concentration, motility, and morphology of sperm isolated from the cauda of the epididymis were evaluated. The ability of the calcium ionophore (A23187) to induce acrosome reaction (AR) in the sperm of WT and IL-1 Ra KO mice was compared with their ability to fertilize in vitro oocytes from WT females. The direct effect of IL-1alpha and IL-1beta on AR and abnormal morphology in sperm from WT were evaluated. The levels of IL-1alpha and IL-1beta in the testes of WT and IL-1 Ra KO mice were examined by specific ELISA and real-time PCR. Our results show a significant reduction in the capacity of IL-1 Ra KO male mice to fertilize WT females (P < 0.05). Furthermore, the number of offspring in mice fertilized with IL-1 Ra KO male mice was significantly lower than with WT males (P < 0.05). Sperm concentration and the percentage of motile sperm from IL-1 Ra KO and WT were similar; however, the percentage of sperm with abnormal morphology (mainly in the head) and acrosome-reacted sperm cells were significantly higher in the IL-1 Ra KO, compared with that of WT males (P < 0.05). In vitro, the ability of sperm from IL-1 Ra KO male mice to fertilize oocytes from WT females was significantly lower than sperm from WT mice (P < 0.05). In addition, the percentage of reacted sperm from IL-1 Ra KO, spontaneously without ionophore induction, was significantly higher than from WT (P < 0.05). Sperm from WT underwent induction of AR only by ionophore; however, sperm from IL-1 Ra KO were unable to undergo the AR by ionophore, indicating that they are induced and, thus, are inactive in fertilization. Testicular IL-1alpha and IL-1beta levels were significantly higher in IL-1 Ra KO, compared with WT male mice (P < 0.05). The addition of recombinant IL-1alpha or IL-1beta to sperm from a WT mouse induced their AR, and significantly increased abnormal sperm morphology, as compared with controls (P < 0.05). This effect was neutralized by the addition of IL-1 Ra. Our results indicate the involvement of IL-1 in sperm physiology, affecting its morphology and fertilization ability. Higher than homeostatic levels of IL-1 in the testis, as observed in IL-1 Ra KO mice, impaired the ability of sperm to fertilize oocytes. Together, these results may explain some of the male infertility cases with an infection/inflammation background and may hint at the ability to use IL-1 Ra in future therapeutic strategies in these cases.

Mechanisms Regulating Spontaneous Contractions in the Bovine Epididymal Duct1

Muscular autorhythmicity provides propulsion of spermatozoa through the epididymal duct, thereby ensuring sperm maturation. In the present study, the mechanisms underlying the bovine epididymal spontaneous phasic contractions (SCs) were analyzed by using muscle-tension recording and patch-clamp techniques. SCs were recorded from the caput, the corpus, and the proximal cauda region and found to be predominantly myogenic in origin. Removal of the luminal fluid induced a burstlike contraction pattern, and removal of the epithelium, a complete loss of SCs. Application of nifedipine, but not heparin and cyclopiazonic acid, suppressed SCs, indicating that influx of Ca2+ through L-type Ca2+ channels, but not Ca2+ release from intracellular stores, was crucial for maintaining SCs. The prostaglandin-endoperoxide synthase 2 (PTGS2) inhibitor NS-398 caused a region-dependent decrease in SCs and tone. These effects were mimicked by the mitogen-activated protein kinase (MAPK) kinase inhibitor PD-98059. Similarly, the prostaglandin F(2alpha) (PGF(2alpha))-receptor antagonist AL-8810 reduced SC generation, whereas PGF(2alpha) induced SC-like activity in epithelium-denuded segments. Cell-isolation experiments revealed the existence of three morphologically different types of contractile cells, which also showed distinct biophysical properties: typical smooth muscle cells in the cauda, myofibroblast-like cells all along the duct, and atypical muscle cells (ATMs) with filament-like spurs in all regions with SCs. These data suggest that the bovine epididymal autorhythmicity is based on an epithelial PTGS2-dependent release of (an) excitatory prostaglandin(s) and a MAPK-dependent activation of L-type Ca2+ channels in the contractile cells. ATM cells may provide electrical coupling between myofibroblasts, which is essential for the generation of regular myogenic activity.

Induction of IL-1, in the Testes of Adult Mice, Following Subcutaneous Administration of Turpentine

PROBLEM

Interleukin-1 family is present in the testicular homogenates and its cellular compartments. It has been suggested that IL-1 is involved in physiological and pathological functions of the testicular tissues. In the present study we examined the effect of acute mostly localized inflammation, using turpentine, on the expression levels of testicular IL-1 system.

METHODS OF STUDY

Mice were subcutaneously injected with steam-distilled turpentine or saline (control). Three hours to 10 days following the injection, mice were killed and testis and spleen were homogenized and examined for interleukin (IL)-1alpha, IL-1beta, and IL-1 receptor antagonist (IL-1ra) levels by enzyme-linked immunosorbent assay and polymerase chain reaction.

RESULTS

Subcutaneous injection of turpentine induced mice systemic inflammation, as indicated by significant increase in serum IL-1beta levels, and IL-1alpha, IL-1beta and IL-1ra in spleen homogenates. The levels of IL-1alpha, IL-1beta and IL-1ra were significantly induced in testicular homogenates of adult mice following subcutaneous injection of turpentine. The significant induction of testicular IL-1alpha was detected after 3-24 hr of turpentine injection and decreased later (after 3-10 days) to levels similar to the control. However, significant induction of testicular IL-1beta was detected only after 3-10 days of turpentine injection, and for testicular IL-1ra levels was detected after 3 hr to 6 days of turpentine injection, and after 10 days the levels were similar to the control. These results were also confirmed by mRNA expression of these factors.

CONCLUSION

Our results demonstrate for the first time the distant effect of acute localized inflammation on testicular IL-1 levels. Thus, transient inflammatory response to infectious/inflammatory agents at non-testicular sites that elicit systemic IL-1 response should be considered during clinical treatment as a possible factor of male infertility.

Hypochlorous acid-induced stress on human spermatozoa

The fertilising ability of human spermatozoa may be impaired by inflammations of the genital tract, although details of these processes are still unknown. Hypochlorous acid (HOCl), an important product of myeloperoxidase released from stimulated neutrophils, induces a concentration-dependent increase in externalisation of phosphatidylserine in ejaculated human spermatozoa as revealed by fluorescence-activated cell sorting (FACS) analysis. The increase of annexin-V binding cells starts already at about 10(-5) mol/l HOCl, while a formation of lysophosphatidylcholines as detected by matrix-assisted laser desorption and ionisation time-of-flight mass spectrometry (MALDI-TOF MS) is only found at HOCl concentrations higher than 10(-4) mol/l. Thus, changes in lipid composition of spermatozoa are unlikely responsible for the phosphatidylcholine (PS)-externalisation. These data gave concomitant evidence that HOCl itself leads to a dramatic damage of the cell membrane. Thus, the neutrophil-derived HOCl contributes to the deterioration of spermatozoa leading to diminished fertilisation ability.

Relationship of interleukin-6 with semen characteristics and oxidative stress in patients with varicocele

OBJECTIVES

To examine levels of interleukin-6 (IL-6) in fertile semen donors and patients with varicocele and examine its association with semen characteristics and levels of reactive oxygen species (ROS).

METHODS

We conducted a prospective study consisting of 15 fertile donors (controls) and 35 infertile patients with varicocele. Semen analysis was performed according to the World Health Organization guidelines. IL-6 levels were measured using the enzyme-linked immunosorbent assay. ROS (x10(4) counted photons per minute per 20 x 10(6) sperm) and total antioxidant capacity (molar trolox equivalents) were measured using a chemiluminescence assay.

RESULTS

The sperm concentration and motility were significantly greater in the donors compared with the infertile patients with varicocele (P <0.0001 and P = 0.01, respectively). The IL-6 (log10 [IL-6 +1]) and ROS (log10 [ROS +1]) levels were significantly greater in infertile patients with varicocele than in the donors (IL-6: 2.1 [1.7, 2.4] versus 0.7 [0, 1.9], P = 0.003; ROS: 1.8 [1.2, 2.6] versus 1.0 [0.7, 1.6], P = 0.04). The total antioxidant capacity levels were significantly lower in the varicocele patients (1166.7 +/- 366.2) than in the donors (1556.4 +/- 468.1; P = 0.003). The IL-6 levels correlated significantly with the ROS levels in the infertile patients with varicocele (r = -0.39; P = 0.01).

CONCLUSIONS

Infertile patients with varicocele exhibited elevated levels of IL-6 and ROS and decreased levels of total antioxidant capacity. Pro-inflammatory cytokine IL-6 and oxidative stress may play a role in the pathophysiology of infertility in these patients.

Male genital tract infection: an influence of leukocytes and bacteria on semen

We have studied the oxidative status of 155 semen samples, 95 originating from healthy individuals and 60 from infertile patients, which were subdivided into two groups: (a) normozoospermic with genitourinary tract infection (GTI); and (b) with pathological spermiogram and GTI. Several phases of infection were observed: with bacterial presence only, bacteria and leukocytes, and leukocytes only, following the routine inflammatory pattern. Leukocyte numbers, bacterial strains, pro- and anti-oxidants, and selected pro-inflammatory cytokines (IL-1 beta, IL-6, IL-8 and TNF-alpha) were studied. Additionally, two oxido-sensitive indices were created (SOD/XO and CAT/XO) in order to follow particular phases of semen infection in two subgroups of patients. Different patterns of activities of pro- and anti-oxidant substances, as well as cytokines, were observed in the studied populations. It was reflected mainly by elevated XO activity in a group of patients with a pathological spermiogram while, in a group of patients with GTI and normozoospermia, xanthine oxidase was normal. In the latter group, oxido-sensitive indices were elevated in favour of anti-oxidants; similarly, this occurred with IL-6 levels in comparison to healthy controls. It appears therefore that normozoospermic semen recovers better after infection than pathological semen. Perhaps, IL-6 secretion might be helpful in the observed recovery?

Interferon-α-like biological activity in human seminal plasma, follicular fluid, embryo culture medium, amniotic fluid and fetal blood

Interferons (IFNs) are a group of cytokines exhibiting antiviral, antiproliferative and immunoregulatory properties. The principal stimulus for the synthesis of IFNs is the presence of viral double-stranded RNA, although rare examples of constitutive synthesis have also been described. The aim of the present study was to determine IFN-α-like biological activity in the seminal plasma, follicular and amniotic fluid, embryo culture medium, and fetal blood obtained from patients without apparent viral or bacterial infections. Interferon-α-like biological activity was determined by a standard cytopathic effect inhibition bioassay. The study included two groups of patients. The first group consisted of 30 married couples participating in the programme for assisted reproduction and the second group consisted of 23 patients scheduled for prenatal diagnosis (15 for amniocentesis and eight for cordocentesis). The seminal plasma of infertile men (asthenozoospermia, oligoasthenozoospermia) contained a high titre of IFN-α-like antiviral activity. Asthenozoospermia was diagnosed in men with a normal sperm concentration but less than 50% progressively motile sperm and oligoasthenozoospermia was diagnosed in men with a sperm count less than 1 × 106 mL−1. Despite slightly higher antiviral titres in the seminal plasma obtained from asthenozoospermic patients, no clear association between IFN-α-like biological activity and sperm concentration was found. Interferon-α-like biological activity was found in all samples of follicular and amniotic fluid and in fetal blood of patients with intrauterine growth retardation and trisomy 18. Antiviral titres from seminal plasma and follicular fluids were significantly higher compared with amniotic fluids and fetal blood. Embryo culture medium did not contain IFN-α-like biological activity. Our results demonstrate that IFN-α-like activity in biological fluids is relevant for reproduction, even in the absence of infection.

Expression of IL-2alpha and IL-2beta receptors on the membrane surface of human sperm

Cytokines are secreted proteins that act as local immunological mediators. Increased seminal cytokine concentrations are associated with fertility problems. The purpose of the present study was to investigate the presence of IL-2alpha, and IL-2beta receptors on fresh and isolated sperm by flow cytometry and transmission electron microscopy. Twenty sperm samples from oligospermic men were incubated with CD25, a mouse monoclonal antibody specific for IL-2alpha-chain receptor, and CD122, a mouse monoclonal antibody specific for IL-2beta-chain receptor. The strong initial fluorescence intensity and, subsequently, a labeling index yielded by CD25 and CD122 decreased in sperm centrifuged on a Percoll gradient (p < .05). The expression of CD25 and CD122 correlated negatively with fresh sperm concentration, but in sperm centrifuged on a Percoll gradient there was no correlation. Labeling with CD25 and CD122 antibody was evident on the head and the middle piece in fresh sperm, while in sperm centrifuged on a Percoll gradient a weak labeling was observed only on the principal piece. The authors have identified and localized cytokine receptors on human sperm for the first time. Cytokine receptors may be involved in the regulation of pathophysiological events in sperm cell functions and male infertility. The exact pathway involved in modulation of these receptors requires further investigation. These results contribute to the understanding of cytokine-sperm relationships.

Involvement of intratesticular IL-1 system in the regulation of Sertoli cell functions

The Interleukin-1 (IL-1) system has been suggested to be involved in the cell-cell cross talk within the testis. To investigate the testicular autocrine, paracrine and endocrine factors involved in the regulation of Sertoli cell functions, we have examined the capacity of Sertoli cell cultures, from immature mice, to produce IL-1alpha, IL-1beta and IL-1 receptor antagonist (IL-1ra) under in vitro cultures and in the presence of testicular physiological and pathological factors. Our investigation revealed that Sertoli cells produce large amounts of IL-1alpha, IL-1ra but not IL-1beta under basal culture conditions, as examined by ELISA and immunohistochemical staining. Liposaccharides (LPS), as well as IL-1alpha and IL-1beta were found to stimulate IL-1alpha and IL-1ra, but not IL-1beta production, in Sertoli cells from immature mice. Maximum concentration of IL-1alpha and of IL-1ra was observed after 2 and 8 h after the stimulation, respectively. The addition of IL-1ra to Sertoli cells did not alter their capacity to constitutively produce IL-1alpha. However, the stimulatory effects of recombinant IL-1alpha on IL-1alpha production by Sertoli cells were reversed by the concomitant addition of recombinant IL-1ra. FSH is capable to induce IL-1ra production in Sertoli cells in a dose-dependent manner but not IL-1alpha or IL-1beta. As expected, Sertoli cell cultures were also shown to constitutively secrete transferrin. Stimulation of these cultures with IL-1alpha, IL-1beta significantly increased their capacity to secrete transferrin. Addition of IL-1ra to unstimulated Sertoli cell cultures did not affect their capacity to secrete transferrin. Stimulation of Sertoli cell cultures with a combination of both IL-1alpha and FSH or IL-1beta and FSH showed additive effect between IL-1 and FSH in their capacity to induce transferrin secretion by these cells. However, stimulation of Sertoli cells with a combination of both IL-1ra and FSH did not affect their capacity to secrete transferrin as compared with FSH-stimulated cultures. Our results with Sertoli cells, in addition to previous data on Lydig cell and germ cells, may suggest the involvement of the IL-1 system in testicular paracrine/autocrine regulation, which could be involved in the regulation of spermatogenesis and spermiogenesis processes and male fertility.

Induction of transferrin secretion in murine Sertoli cells by FSH and IL-1: the possibility of different mechanism(s) of regulation

In the present study we examined the capacity of interleukin-1 (IL-1) alpha, beta, interleukin-1 receptor antagonist (IL-1ra) and follicle stimulating hormone (FSH) to induce transferrin secretion by Sertoli cells under in vitro conditions. Primary Sertoli cell (SC) cultures from immature mice secreted constitutively transferrin. Stimulation of these cultures with IL-1alpha, IL-1beta significantly increas\d their capacity to secrete transferrin. Addition of IL-1ra to unstimulated SC cultures did not affect their capacity to secrete transferrin. Stimulation of SC cultures with a combination of both IL-1alpha and FSH or IL-1beta and FSH showed additive effect between IL-1 and FSH in their capacity to induce transferrin secretion by these cells. However, stimulation of Sertoli cells with a combination of both IL-1ra and FSH did not affect their capacity to secrete transferrin compared with FSH-stimulated cultures. Our results may suggest the involvement of testicular paracrine/autocrine factors (IL-1) and endocrine (FSH) factors in the regulation of transferrin secretion by SC. This capacity seems to be differently regulated by these factors. Thus, IL-1alpha and beta may directly affect physiological functions of the testis; which may suggest their involvement in the regulation of spermatogenesis and spermiogenesis processes and male fertility.

The lipopolysaccharide co-receptor CD14 is present and functional in seminal plasma and expressed on spermatozoa

CD14 is a 54 000-molecular weight (MW) glycolipid-anchored membrane glycoprotein, expressed on myeloid cells, which functions as a member of the lipopolysaccharide (LPS) receptor complex. Soluble forms of CD14 have been reported in plasma, cerebrospinal fluid, amniotic fluid and breast milk. In plasma and breast milk, soluble CD14 has been implicated as a regulator of T- and B-cell activation and function. Expression of CD14 in the male reproductive system has not previously been investigated. We here show that soluble CD14 is present in seminal plasma at levels comparable to those in serum. Spermatozoa expressed CD14 on their membranes, as demonstrated by fluorescence microscopy and flow cytometry. Post-vasectomy, the levels of seminal plasma CD14 (spCD14) were much reduced, implying an origin distal to the point of transection of the vas deferens. Ultracentrifugation analyses demonstrated that spCD14 was not associated with lipid complexes, indicating that it lacks the glycolipid anchor. Purified spCD14 mediated activation by LPS of CD14-negative cells. These findings suggest that CD14 may play a hitherto unexplored role in immune defence and cell activation in the male reproductive tract.