Presence of IL-18 in testicular tissue of fertile and infertile men

Possible Impact of Human β-defensin 1 on sperm motility in infertile men with abnormal sperm parameters

Human β-defensins and interleukins may be auxiliary in sperm maturation. This cross-sectional study aimed to evaluate the expression of Human β-defensins 1 and 2, interleukins (ILs)- 10 and -18 genes in sperm, as well as seminal plasma levels of these two cytokines in subfertile men with different types of sperm abnormalities compared to those with normozoospermic men. Participants were separated into two experimental groups: the control group (n = 25) and the group with sperm abnormalities (SA) (n = 45). SA participants were further subdivided into the following groups with n = 15 individuals each: Teratozoospermia (T), Asthenoteratozoospermia (AT), and Oligoasthenoteratozoospermia (OAT) groups. The quantitative real-time polymerase chain reaction was used to quantify the mRNA levels of hBDs 1 and 2, IL-10, and IL-18 in sperm. The seminal plasma concentrations of IL-10 and IL-18 were measured by using the enzyme-linked immunosorbent assay technique. The mRNA expression of hBD-1 and IL-10 showed a significant decrease in the OAT compared to the controls (P < 0.0001 and P = 0.02, respectively). The lowest seminal plasma concentration of IL-10 belonged to the OAT (P = 0.04). ROC curve analysis showed a sensitivity, specificity, and cutoff value of 82.35%, 86.67%, and 0.63 for hBD-1 levels, respectively. A positive and significant correlation was found between hBD-1 expression and sperm motility and IL-10 expression rate and normal sperm morphology.Therefore, hBD-1 could be considered as the alternative biomaterial to pre-treatments of infertile men with abnormal sperm parameters, specifically OAT men, which led to improving the assisted reproduction success rate.

The role of death receptor signaling pathways in mouse Sertoli cell avoidance of apoptosis during LPS- and IL-18-induced inflammatory conditions

Lipopolysaccharide (LPS) triggers infectious acute inflammation, and interleukin (IL)-18 is an inflammasome-mediated cytokine. We previously demonstrated that endogenous IL-18 induces testicular germ cell apoptosis during acute inflammation when plasma IL-18 levels are high. Additionally, high-dose recombinant IL-18 (rIL-18) induced Leydig cell apoptosis. The blood-testis barrier formed by Sertoli cells protects testicular germ cells from both exogenous and endogenous harmful substances. However, the impact of LPS and IL-18 on Sertoli cells remained unclear. We stimulated TM4 cells, a mouse Sertoli cell line, with LPS (200 or 1000 ng/mL) or rIL-18 (0.1-100 ng/mL) at levels that induced Leydig cell apoptosis in our previous study and assessed caspase 3 cleavage and the mRNA expression of inflammatory cytokines and markers of apoptotic pathways (Tnfr1, Fasl, Fas, Fadd) after stimulation. Il6 mRNA was increased by LPS stimulation. Tnfα mRNA was increased by 200 ng/mL LPS but not 1000 ng/mL LPS. Fas was increased, but Fasl was decreased, by LPS. LPS had little influence on Tnfr1 or Fadd mRNA expression and did not induce apoptosis. Il18 mRNA was not increased, and Il18r1 was significantly decreased following LPS treatment. Treatment with rIL-18 increased Il18r1 mRNA and induced inflammation, but decreased Tnfr1 and had little influence on apoptosis, as indicated by Tnfα, Fasl, Fas, Fadd and cleaved caspase 3. These results suggested that Sertoli cells do not easily undergo apoptosis despite strong inflammatory stimuli. Additionally, Sertoli cells may resist inflammation and play a larger role in protecting testicular homeostasis than other component cells of the testis.

Quercetin Ameliorates Testicular Damage in Zucker Diabetic Fatty Rats through Its Antioxidant, Anti-Inflammatory and Anti-Apoptotic Properties

The aim of this study was to investigate the effects of quercetin (QUE) on the testicular architecture as well as markers of oxidative, inflammatory, and apoptotic profile of male gonads in Zucker diabetic fatty (ZDF) rats suffering from Type 2 diabetes mellitus in the absence or presence of obesity. QUE was administered orally at a dose of 20 mg/kg/day for 6 weeks. Morphometric analysis revealed that QUE treatment led to an improvement in testicular appearance, particularly in the case of Obese ZDF rats. Furthermore, a significant stabilization of the antioxidant capacity (p < 0.05), superoxide dismutase and catalase activity (p < 0.01), with a concomitant decrease in lipid peroxidation (p < 0.05) were observed in Obese ZDF animals exposed to QUE. Our data also indicate a significant decline in the levels of interleukin (IL)-1 (p < 0.05), IL-6 (p < 0.01) and tumor necrosis factor alpha (p < 0.001) following QUE supplementation to Obese ZDF rats in comparison with their respective control. Finally, a significant down-regulation of the pro-apoptotic BAX protein (p < 0.0001) was observed in Obese ZDF rats administered with QUE, while a significant Bcl-2 protein overexpression (p < 0.0001) was recorded in Lean ZDF animals when compared to their untreated control. As such, our results suggest that QUE is a potentially beneficial agent to reduce testicular damage in ZDF rats with Type 2 diabetes mellitus by decreasing oxidative stress, chronic inflammation, and excessive cell loss through apoptosis.

Characterization of the structural, oxidative, and immunological features of testis tissue from Zucker diabetic fatty rats

The purpose of this study was to characterize the testicular profile of Zucker diabetic fatty (ZDF) rats presenting with type 2 diabetes mellitus (DM2) in the absence or presence of obesity. To achieve this, testes were collected from 270-day-old male Wistar (n = 15), ZDF nonobese (n = 15), and ZDF obese rats (n = 16). Changes to the testicular structure were quantified morphometrically, while immunocytochemistry was employed to assess caspase-3 activity. Reactive oxygen species (ROS) production, fluctuations of major antioxidant molecules, and the extent of damage to the proteins and lipids were assessed in tissue lysates. Levels of selected interleukins (ILs) were determined by enzyme-linked immunosorbent assay. The results reveal significant alterations to the testicular structure accompanied by caspase-3 overexpression, particularly in ZDF obese rats. The most notable disruption of the oxidative balance, characterized by ROS overproduction, antioxidant deficiency, protein, and lipid deterioration was recorded in ZDF rats suffering from both DM2 and obesity. Accordingly, the highest concentrations of pro-inflammatory IL-1, IL-6, and IL-18 accompanied by reduced levels of the anti-inflammatory IL-10 were found in testicular tissue collected from ZDF obese rats. This study highlights the vulnerability of male gonads to pathophysiological changes caused by hyperglycemia, which are further exacerbated by excessive adipose tissue.

The NLRP3 inflammasome: molecular activation and regulation in spermatogenesis and male infertility; a systematic review

Background

Infertility related to varicocele, infections, metabolic dysfunctions, oxidative stress and environmental toxicants is also associated with inflammatory processes that ultimately lead to the activation of the inflammasome pathway (IP). IP is classically activated by DAMPs, MAMPs or LAMPs, which stand for Damage-, Microbe- or Lifestyle-Associated Molecular Patterns, respectively. The most important player in IP activation is the NLRP3 (NOD[Nuclear oligomerization domain]-, LRR[Leucine rich repeat]- and pyrin domain-containing protein 3) which functions as an intracellular sensor of D/M/L-AMPs resulting in activation of caspase-1, promotion of apoptosis, pyroptosis and generation of inflammatory cytokines. This review addresses the question of whether IP activation might be associated with male infertility situations.

Results & conclusions

We conducted a systematic review of articles published in the Google Scholar, and PubMed databases through October 2021. It turns out that inflammasome activation and its consequences including cytokine storms, apoptosis and pyroptosis could be associated with the reduced sperm count as well as the structural and functional sperm defects recorded in several situations associated with male infertility suggesting that anti-inflammatory therapeutic strategies could be possibly considered to restore male fertility in future research.

The Heritability of Behaviors Associated With the Host Gut Microbiota

What defines whether the interaction between environment and organism creates a genetic memory able to be transferred to subsequent generations? Bacteria and the products of their metabolism are the most ubiquitous biotic environments to which every living organism is exposed. Both microbiota and host establish a framework where environmental and genetic factors are integrated to produce adaptive life traits, some of which can be inherited. Thus, the interplay between host and microbe is a powerful model to study how phenotypic plasticity is inherited. Communication between host and microbe can occur through diverse molecules such as small RNAs (sRNAs) and the RNA interference machinery, which have emerged as mediators and carriers of heritable environmentally induced responses. Notwithstanding, it is still unclear how the organism integrates sRNA signaling between different tissues to orchestrate a systemic bacterially induced response that can be inherited. Here we discuss current evidence of heritability produced by the intestinal microbiota from several species. Neurons and gut are the sensing systems involved in transmitting changes through transcriptional and post-transcriptional modifications to the gonads. Germ cells express inflammatory receptors, and their development and function are regulated by host and bacterial metabolites and sRNAs thus suggesting that the dynamic interplay between host and microbe underlies the host's capacity to transmit heritable behaviors. We discuss how the host detects changes in the microbiota that can modulate germ cells genomic functions. We also explore the nature of the interactions that leave permanent or long-term memory in the host and propose mechanisms by which the microbiota can regulate the development and epigenetic reprogramming of germ cells, thus influencing the inheritance of the host. We highlight the vast contribution of the bacterivore nematode C. elegans and its commensal and pathogenic bacteria to the understanding on how behavioral adaptations can be inter and transgenerational inherited.

Interleukin-18 levels and mouse Leydig cell apoptosis during lipopolysaccharide-induced acute inflammatory conditions

Interleukin (IL)-18 is an inflammasome-mediated cytokine produced by germ cells, Leydig cells, and resident macrophages that is indispensable in the maintenance of homeostasis in the testis. We previously demonstrated that endogenous IL-18 induces testicular germ cell apoptosis during acute inflammation when plasma IL-18 levels are very high. However, the impact of acute inflammation and IL-18 on Leydig cells remained unclear. TM3 cells, a mouse Leydig cell line, and RAW264.7 cells, a mouse macrophage cell line, were stimulated with lipopolysaccharide (LPS) or recombinant IL-18 (rIL-18). We assessed the expression of inflammatory cytokines, caspase cleavage, and markers of apoptotic pathways. In Leydig cells, caspase 3 cleavage was increased and death-receptor-mediated apoptotic pathways were activated after LPS stimulation. However, LPS stimulation did not increase IL-18 expression in the Leydig cell line. When high-dose rIL-18 was administered to the Leydig cell line to mimic levels seem after inflammation, rIL-18 upregulated Tnf-α mRNA, Fadd mRNA, and Fas protein, promoted cleavage of caspase-8 and caspase-3, and induced apoptosis. Low-dose rIL-18 did not stimulate apoptosis. To determine if the high level of IL-18 seen in the testes after inflammation was derived from immune cells, we examined IL-18 protein expression in a macrophage cell line, RAW264.7. In contrast to the TM3 cells, IL-18 was significantly increased in RAW264.7 cells after LPS stimulation. These results suggest that high-dose IL-18 derived from macrophages is harmful to Leydig cells. Reducing the overexpression of IL-18 could be a new therapeutic approach to prevent Leydig cell apoptosis as a result of acute inflammation.

Expression of mRNA and protein of IL-18 and its receptor in human follicular granulosa cells

PURPOSE

There is no information available about the IL-18 receptor in ovarian follicles, so the present study attempts to demonstrate the expression of IL-18 and its receptor in human granulosa cells (GCs).

METHODS

To evaluate the concentration of IL-18 in serum and follicular fluid (FF), we collected serum and FF from 102 women undergoing oocyte retrieval. Also, to detect expression of IL-18 and its receptor by luteinized GCs, these cells were pooled six times from a total of twenty individual patients with 5-16 follicles each. The IL-18 concentration was determined by ELISA and the expression of IL-18 and its receptor by immunocytochemistry and reverse transcription polymerase chain reaction.

RESULTS

Our results showed that the median IL-18 concentration in serum, 159.27 pg/ml (IQR 121.41-210.1), was significantly higher than in FF, 142.1 pg/ml (IQR 95.7-176.5), p < 0.001. Moreover, we found that IL-18 and its receptor are expressed by GCs.

CONCLUSION

The presence of IL-18 in FF and the expression of IL-18 and its receptor by GCs suggest an important role for this cytokine in ovarian function.

Cytokines in the blood and semen of infertile patients

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

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

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

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

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

Interleukin-18 gene polymorphisms and risk of recurrent pregnancy loss: A systematic review and meta-analysis

Interleukin-18 (IL-18) plays a potential pathological role in recurrent pregnancy loss (RPL). The results of published studies on the relationship between IL-18 gene promoter polymorphisms (-137G/C and-607C/A) and RPL risk remain controversial. This meta-analysis was performed to evaluate the association of IL-18, -137G/C and-607C/A gene polymorphisms with the risk of RPL under recessive, dominant and additive genetic models. A literature search was conducted in Medline, Embase and Web of Science for studies that described the effect of IL-18 gene polymorphisms on RPL risk. The numbers of each -137G/C and-607C/A genotype in the case and control groups were extracted. Quality of the original studies' methodology was also assessed. Meta-analysis was performed using Stata 13.1 software and the fixed effect model was used. Five articles were included in this meta-analysis. No significant heterogeneity between the studies was noted. The IL-18 -137 G/C polymorphism was significantly associated with an increased risk of RPL under a recessive genetic model (CC vs. GG + CG: odds ratio = 1.56, 95% confidence interval = 1.13 ~ 2.15). For the -607C/A mutation, we failed to find any association under any genetic models. The Egger's regression asymmetry test showed no publication bias. Our present study indicates a positive association between the CC genotype of the IL-18 -137G/C gene and RPL risk. Future well-designed large studies are needed to validate the association between IL-18 gene polymorphisms and the risk of RPL.

Endogenous interleukin 18 regulates testicular germ cell apoptosis during endotoxemia

Orchitis (testicular swelling) often occurs during systemic inflammatory conditions, such as sepsis. Interleukin 18 (IL18) is a proinflammatory cytokine and is an apoptotic mediator during endotoxemia, but the role of IL18 in response to inflammation in the testes was unclear. WT and IL18 knockout (KO) mice were injected lipopolysaccharide (LPS) to induce endotoxemia and examined 12 and 48  h after LPS administration to model the acute and recovery phases of endotoxemia. Caspase activation was assessed using immunohistochemistry. Protein and mRNA expression were examined by western blot and quantitative real-time RT-PCR respectively. During the acute phase of endotoxemia, apoptosis (as indicated by caspase-3 cleavage) was increased in WT mice but not in IL18 KO mice. The death receptor-mediated and mitochondrial-mediated apoptotic pathways were both activated in the WT mice but not in the KO mice. During the recovery phase of endotoxemia, apoptosis was observed in the IL18 KO mice but not in the WT mice. Activation of the death-receptor mediated apoptotic pathway could be seen in the IL18 KO mice but not the WT mice. These results suggested that endogenous IL18 induces germ cell apoptosis via death receptor mediated- and mitochondrial-mediated pathways during the acute phase of endotoxemia and suppresses germ cell apoptosis via death-receptor mediated pathways during recovery from endotoxemia. Taken together, IL18 could be a new therapeutic target to prevent orchitis during endotoxemia.

AR3 messenger ribonucleic acid expression and its functional implication in human primary testicular failure

AR3, a major one of androgen receptor (AR) splice variants, has been shown to play a pivotal role in concert with AR signalling in prostate cancer. The present study was undertaken to characterise the expression pattern of AR3 in normal and impaired spermatogenesis. Expression of AR3 mRNA showed significantly lower level in testicular tissues with impaired spermatogenesis when compared to normal tissues. This aberrant expression profile of AR3 in human pathological testes was further confirmed by immunoblotting analysis. Moreover, in situ hybridisation studies revealed that the transcripts of the gene were dominantly localised in the pachytene spermatocytes and round spermatids, suggesting a potential involvement of this transcriptional regulator in the auto-/paracrine regulation of meiotic and post-meiotic differentiation. This hypothesis was strengthened by the observation that AR3 mRNA expression was positively correlated to average seminiferous tubule score and was negatively correlated to serum FSH level. To the best of our knowledge, such a distinct expression profile of AR3 has not been reported previously in human testis. Overall, our data are suggestive of a novel site of action of AR3 during human spermatogenesis and should shed light on the complicated circuit composed of AR and its splice variants.

The gene expression analysis of paracrine/autocrine factors in patients with spermatogenetic failure compared with normal spermatogenesis

PROBLEM

The aim of this study was to examine the expression levels of IL-1 family members, IL-6, IL-10, TNF family, SCF, and c-kit in infertile patients with idiopathic non-obstructive azoospermia (NOA) compared with men with normal spermatogenesis.

METHOD OF STUDY

We analyzed 20 testicular biopsy samples with Affymetrix Human Gene 1.0 ST microarrays (Affymetrix, Santa Clara, CA, USA). Sixteen of them were obtained from patients with various types of NOA and four with normal spermatogenesis.

RESULTS

The comparative analysis of normal and pathological group demonstrated a different expression level of IL1-RA gene. It was also observed that the gene expression levels for IL1-R1, CASP1, and stem cell factor (SCF) were upregulated in the Sertoli-cell-only syndrome group in comparison with the control one (P < 0.05).

CONCLUSION

The microarray analysis showed the expression level of all investigated paracrine/autocrine factors at one go, and therefore, the possible interaction between these genes could be examined.