Induction of interleukin-1alpha production in murine Sertoli cells by interleukin-1

Cadmium exposure induces pyroptosis of TM4 cells through oxidative stress damage and inflammasome activation

Cadmium (Cd) is a harmful metal that seriously affects the male reproductive system, but the mechanism of how Cd exposure damages Sertoli cells is not fully understood. This study used TM4 cells to explore the mechanism of Cd damage to Sertoli cells. We found that Cd was concentration- and time-dependent on TM4 cell viability. Cd exposure increased intracellular reactive oxygen species (ROS) levels, lactate dehydrogenase (LDH), and Interleukin-1β (IL-1β) release in TM4 cells, decreased mitochondrial function, and increased pyroptosis. N-acetylcysteine (NAC), MCC950 and BAY 11-7082 (BAY) alleviate the release of IL-1β and LDH induced by Cd. NAC reduced Cd induced increases in ROS, NLRP3, Caspase-1, Heme oxygenase-1(HO-1), superoxide dismutase (SOD2), and increased mitochondrial function. The activation of GSDMD is the main causes of pyroptosis, and NAC significantly inhibit its activation and formation. Our results suggest that Cd exposure induces a toxic mechanism of GSDMD-mediated pyroptosis in TM4 cells by increasing ROS levels and activating the inflammasome.

Leukemia and male infertility: past, present, and future

Spermatogenesis is the process of the proliferation and differentiation of spermatogonial stem cells (SSCs) to generate sperm. Leukemia patients show impairment in some of the endocrine hormones that are involved in spermatogenesis. They also show a decrease in semen parameters before and after thawing of cryopreserved samples compared to a control. The mechanisms behind these effects have not yet been described. This review summarizes the effect of leukemia on semen parameters from adult patients and highlights feasible suggested mechanisms that may affect impairment of spermatogenesis in these patients. We suggest the possible involvement of leukemia in disturbing hormones involved in spermatogenesis, and the imbalance in testicular paracrine/autocrine factors involved in the formation of SSC niches that control their proliferation and differentiation. Understanding the mechanisms of leukemia in the impairment of spermatogenesis may lead to the development of novel therapeutic strategies mainly for prepubertal boys who do not yet produce sperm.

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.

Surfing the wave, cycle, life history, and genes/proteins expressed by testicular germ cells. Part 5: intercellular junctions and contacts between germs cells and Sertoli cells and their regulatory interactions, testicular cholesterol, and genes/proteins associated with more than one germ cell generation

In the testis, cell adhesion and junctional molecules permit specific interactions and intracellular communication between germ and Sertoli cells and apposed Sertoli cells. Among the many adhesion family of proteins, NCAM, nectin and nectin-like, catenins, and cadherens will be discussed, along with gap junctions between germ and Sertoli cells and the many members of the connexin family. The blood-testis barrier separates the haploid spermatids from blood borne elements. In the barrier, the intercellular junctions consist of many proteins such as occludin, tricellulin, and claudins. Changes in the expression of cell adhesion molecules are also an essential part of the mechanism that allows germ cells to move from the basal compartment of the seminiferous tubule to the adluminal compartment thus crossing the blood-testis barrier and well-defined proteins have been shown to assist in this process. Several structural components show interactions between germ cells to Sertoli cells such as the ectoplasmic specialization which are more closely related to Sertoli cells and tubulobulbar complexes that are processes of elongating spermatids embedded into Sertoli cells. Germ cells also modify several Sertoli functions and this also appears to be the case for residual bodies. Cholesterol plays a significant role during spermatogenesis and is essential for germ cell development. Lastly, we list genes/proteins that are expressed not only in any one specific generation of germ cells but across more than one generation.

Regulation of interleukin 1alpha, activin and inhibin by lipopolysaccharide in Sertoli cells from prepubertal rats

Bacterial lipopolysaccharide increased the production of interleukin 1alpha and activin A, and reduced production of inhibin B, in Sertoli cells from immature male rats measured by enzyme-linked immunosorbent assay (ELISA). The majority of immunoreactive interleukin 1alpha remained within the Sertoli cell, while both activin A and inhibin B were secreted. Lipopolysaccharide-stimulated expression of two interleukin 1alpha mRNA transcripts, measured by quantitative RT-PCR, but the levels of bioactive interleukin 1alpha in Sertoli cell extracts and medium, measured by in vitro bioassay, were comparatively low to undetectable. A specific antagonist of interleukin 1alpha had no effect on lipopolysaccharide-stimulated activin A or inhibin B responses. These data indicate that, in contrast to Sertoli cells from adult rats, lipopolysaccharide-induced regulation of activin A and inhibin B by prepubertal Sertoli cells does not involve secreted interleukin 1alpha. The data highlight the possibility of a role for intracellular interleukin 1alpha in the Sertoli cell response to inflammation, particularly in the immature testis.

Post-natal changes in testicular concentrations of interleukin-1 alpha and beta and interleukin-6 during sexual maturation in bulls

Based on observations in laboratory animals interleukins could be regulators of testicular development. The objects of this study were to see if interleukins (IL-1 and IL-6) are present in the developing bull testis and to establish the temporal patterns of concentrations of IL-1 and IL-6 in the bovine testis during development. Separate groups of six bull calves were castrated every 4 weeks from 5 to 33 weeks of age, and at 56 weeks of age. Mean testicular IL-1 alpha concentrations decreased (p < 0.01) from 5 to 9 weeks of age and 13 to 21 weeks of age. Mean testicular IL-1 beta concentrations decreased (p < 0.01) from 13 to 17 weeks of age and from 29 to 33 weeks of age. Mean IL-1 bioactivity increased from 13 to 17 weeks of age, decreased to 21 weeks, increased to 25 weeks, decreased to 29 weeks and decreased from 33 to 56 weeks of age (p < 0.05). Mean testicular IL-6 concentrations decreased (p < 0.05) from 9 to 13 weeks of age, increased (p < 0.05) to 21 weeks, decreased (p < 0.05) to 25 weeks, increased (p < 0.05) to 29 weeks and decreased (p < 0.01) to 56 weeks of age. In conclusion, testicular IL-1 alpha, IL-1 beta and IL-6 were found in the bovine testis and concentrations were age dependent. Testicular IL-1 alpha and IL-1 beta concentrations were highest in the early post-natal period; however, IL-1 bioactivity and IL-6 concentrations were greatest in the immediate pre-pubertal period. These findings suggest a functional role for interleukins in testicular development in the bull.

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.

The testis in immune privilege

The production, differentiation, and presence of male gametes represent inimitable challenges to the immune system, as they are unique to the body and appear long after the maturation of the immune system and formation of systemic self-tolerance. Known to protect germ cells and foreign tissue grafts from autoimmune attack, the 'immune privilege' of the testis was originally, and somewhat simplistically, attributed to the existence of the blood-testis barrier. Recent research has shown a previously unknown level of complexity with a multitude of factors, both physical and immunological, necessary for the establishment and maintenance of the immunotolerance in the testis. Besides the blood-testis barrier and a diminished capability of the large testicular resident macrophage population to mount an inflammatory response, it is the constitutive expression of anti-inflammatory cytokines in the testis by immune and particularly somatic cells, that represents an essential element for local immunosuppression. The role of androgens in testicular immune regulation has long been underestimated; yet, accumulating evidence now shows that they orchestrate the inhibition of proinflammatory cytokine expression and shift cytokine balance toward a tolerogenic environment. Furthermore, the role of the testicular dendritic cells in suppressing antigen-specific immunity and T-lymphocyte activation is discussed. Finally, the active role mast cells play in the induction and amplification of immune responses, both in infertile humans and in experimental models, highlights the importance of preventing mast cell activation to maintain the immune-privileged status of the testis.

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.

Use of Sertoli cell transplants to provide local immunoprotection for tissue grafts

The recent success of allogeneic islet transplantation for the treatment of type I diabetes has renewed interest in cell therapy for diseases of secretory cell dysfunction. Unfortunately, widespread clinical use of cell transplantation is limited by tissue availability and the need for long-term immunosuppresion. Testicular Sertoli cells can confer local immunoprotection for co-transplanted cells and may provide a means of overcoming the obstacles associated with cell transplantation. Sertoli cell grafts protect islets in animal models of diabetes and can be transplanted into the brain to enhance regeneration and promote the survival of co-grafted tissues. This review describes the role that Sertoli cells normally play in testicular immunology, details the preclinical data using transplanted Sertoli cells in models of diabetes and Parkinson's disease and discusses some of the possible mechanisms involved in this phenomena, as well as the future of this technology.

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.