Essential pathogenic role for endogenous interferon-gamma (IFN-gamma) during disease onset phase of murine experimental autoimmune orchitis. I. In vivo studies

Testicular immunity

The testis is a unique environment where immune responses are suppressed to allow the development of sperm that possess autoimmunogenic antigens. There are several contributors responsible for testicular immune privilege, including the blood-testis barrier, testicular immune cells, immunomodulation by Sertoli cells, and high levels of steroid hormones. Despite multiple mechanisms in place to regulate the testicular immune environment, pathogens that disrupt testicular immunity can lead to long-term effects such as infertility. If testicular immunity is disturbed, autoimmune reactions can also occur, leading to aberrant immune cell infiltration and subsequent attack of autoimmunogenic germ cells. Here we discuss cellular and molecular factors underlying testicular immunity and how testicular infection or autoimmunity compromise immune privilege. We also describe infections and autoimmune diseases that impact the testis. Further research into testicular immunity will reveal how male fertility is maintained and will help update therapeutic strategies for infertility and other testicular disorders.

Miltefosine enhances infectivity of a miltefosine-resistant Leishmania infantum strain by attenuating its innate immune recognition

Background

Miltefosine (MIL) is currently the only oral drug available to treat visceral leishmaniasis but its use as first-line monotherapy has been compromised by an increasing treatment failure. Despite the scarce number of resistant clinical isolates, MIL-resistance by mutations in a single aminophospholipid transporter gene can easily be selected in a laboratory environment. These mutations result in a reduced survival in the mammalian host, which can partially be restored by exposure to MIL, suggesting a kind of drug-dependency.

Methodology/Principal findings

To enable a combined study of the infection dynamics and underlying immunological events for differential in vivo survival, firefly luciferase (PpyRE9) / red fluorescent protein (DsRed) double-reporter strains were generated of MIL-resistant (MIL-R) and syngeneic MIL-sensitive (MIL-S) Leishmania infantum. Results in C57Bl/6 and BALB/c mice show that MIL-R parasites induce an increased innate immune response that is characterized by enhanced influx and infection of neutrophils, monocytes and dendritic cells in the liver and elevated serum IFN-γ levels, finally resulting in a less efficient establishment in liver macrophages. The elevated IFN-γ levels were shown to originate from an increased response of hepatic NK and NKT cells to the MIL-R parasites. In addition, we demonstrated that MIL could increase the in vivo fitness of MIL-R parasites by lowering NK and NKT cell activation, leading to a reduced IFN-γ production.

Conclusions/Significance

Differential induction of innate immune responses in the liver was found to underlie the attenuated phenotype of a MIL-R parasite and its peculiar feature of drug-dependency. The impact of MIL on hepatic NK and NKT activation and IFN-γ production following recognition of a MIL-R strain indicates that this mechanism may sustain infections with resistant parasites and contribute to treatment failure.

Visceral leishmaniasis is a neglected tropical disease that is fatal if left untreated. Miltefosine is currently the only oral drug available but is increasingly failing to cure patients, resulting in its discontinuation as first-line drug in some endemic areas. To understand these treatment failures, we investigated the complex interplay of the parasite with the host immune system in the presence and absence of miltefosine. Our data indicate that miltefosine-resistant Leishmania parasites become severely hampered in their in vivo infectivity, which could be attributed to the induction of a pronounced innate immune response. Interestingly, the infection deficit was partially restored in the presence of miltefosine. Our results further indicate that miltefosine can exacerbate infections with resistant parasites by reducing innate immune recognition. This study provides new insights into the complex interplay between parasite, drug and host and discloses an immune-related mechanism of treatment failure.

Insights into differentiation and function of the transition region between the seminiferous tubule and rete testis

Seminiferous tubules physically connect to the rete testis through short segments called the transition region (TR). During fetal development, this specialized junction is considered the initial site where testis cords begin to form and to grow in length well beyond birth and into adulthood and form convoluted tubular cores. Mitotic activity of the Sertoli cell, the somatic cell of the epithelium, ceases before puberty, but modified Sertoli cells in the TR remain immature and capable of proliferation. This review presents what is known about this specialized region of the testis, with an emphasis on the morphological, molecular and physiological features, which support the hypothesis that this short region of epithelial transition serves as a specialized niche for undifferentiated Sertoli cells and spermatogonial stem cells. Also, the region is populated by an elevated number of immune cells, suggesting an important activity in monitoring and responding to any leakage of autoantigens, as sperm enter the rete testis. Several structure/function characteristics of the transition region are discussed and compared across species.

The cytokine network in the pathogenesis of major depressive disorder. Close to translation?

Major depressive disorder (MDD) is a common condition that afflicts the general population across a broad spectrum of ages and social backgrounds. MDD has been identified by the World Health Organization as a leading cause of disability worldwide. Approximately 30% of patients are poor responsive to standard of care (SOC) treatment and novel therapeutic approaches are warranted. Since chronic inflammation, as it is often observed in certain cancers, type 2 diabetes, psoriasis and chronic arthritis, are accompanied by depression, it has been suggested that immunoinflammatory processes may be involved in the pathogenesis of MDD. Cytokines are a group of glycoproteins secreted from lymphoid and non-lymphoid cells that orchestrate immune responses. It has been suggested that a dysregulated production of cytokines may be implicated in the pathogenesis and maintenance of MDD. On the basis of their functions, cytokines can be subdivided in pro-inflammatory and anti-inflammatory cytokines. Since abnormal blood and cerebrospinal fluid of both pro and anti-inflammatory cytokines are altered in MDD, it has been suggested that abnormal cytokine homeostasis may be implicated in the pathogenesis of MDD and possibly to induction of therapeutic resistance. We review current data that indicate that cytokines may represent a useful tool to identify MDD patients that may benefit from tailored immunotherapeutic approaches and may represent a potential tailored therapeutic target.

A novel label-free electrochemical impedance aptasensor for highly sensitive detection of human interferon-gamma based on target-induced exonuclease inhibition

In this paper, a novel label-free electrochemical impedance aptasensor for highly sensitive detection of IFN-γ based on target-induced exonuclease inhibition was constructed. For this purpose, we designed a DNA hairpin modified on the gold electrode whose loop was the aptamer of the IFN-γ, and the stem was 5'-thiol-modified. In the absence of IFN-γ, Exonuclease III (Exo III) and Exonuclease I (Exo I) digested the double-stranded and single-stranded strands of the hairpin DNA, respectively, causing smaller impedance value on the surface of the electrode. In the presence of IFN-γ, the function of Exo III was greatly inhibited by the binding of the aptamer with the target, and it stopped after cutting three bases of the hairpin DNA. Forming a major target-bound aptamer digestion product, it could not be digested by Exo I, so there was larger impedance on the electrode surface. The calibration curve for IFN-γ was linear in the range of 1 pM-50 nM with the detection limit (LOD) of 0.7 pM_. The proposed aptasensor proved good selectivity and reproducibility, and low cost. In addition, the biosensor was able to detect IFN-γ in serum samples successfully, which is expected to provide an efficient method for TB diagnosis at early stages.

Chlamydia muridarum infection-induced destruction of male germ cells and sertoli cells is partially prevented by Chlamydia major outer membrane protein-specific immune CD4 cells

Chlamydia trachomatis infections are increasingly prevalent worldwide. Male chlamydial infections are associated with urethritis, epididymitis, and orchitis; however, the role of Chlamydia in prostatitis and male factor infertility remains controversial. Using a model of Chlamydia muridarum infection in male C57BL/6 mice, we investigated the effects of chlamydial infection on spermatogenesis and determined the potential of immune T cells to prevent infection-induced outcomes. Antigen-specific CD4 T cells significantly reduced the infectious burden in the penile urethra, epididymis, and vas deferens. Infection disrupted seminiferous tubules, causing loss of germ cells at 4 and 8 wk after infection, with the most severely affected tubules containing only Sertoli cells. Increased mitotic proliferation, DNA repair, and apoptosis in spermatogonial cells and damaged germ cells were evident in atrophic tubules. Activated caspase 3 (casp3) staining revealed increased (6-fold) numbers of Sertoli cells with abnormal morphology that were casp3 positive in tubules of infected mice, indicating increased levels of apoptosis. Sperm count and motility were both decreased in infected mice, and there was a significant decrease in morphologically normal spermatozoa. Assessment of the spermatogonial stem cell population revealed a decrease in promyelocytic leukemia zinc finger (PLZF)-positive cells in the seminiferous tubules. Interestingly, adoptive transfer of antigen-specific CD4 cells, particularly T-helper 2-like cells, prior to infection prevented these effects in spermatogenesis and Sertoli cells. These data suggest that chlamydial infection adversely affects spermatogenesis and male fertility, and that vaccination can potentially prevent the spread of infection and these adverse outcomes.

Aptamer-based array electrodes for quantitative interferon-γ detection

Present work describes the methylene blue tagged thiolated aptamer-modified gold micro-array based biosensor for specific detection of IFN-γ. The microchips with the microelectrode array were fabricated using standard silicon microfabrication technologies, and modified with methylene blue tagged aptamer using standard gold thiol chemistry. Electrodes were characterized and tested using Cyclic Voltammetric (CV) and Square Wave Voltammetry (SQW) measurements in a standard three-electrode format at room temperature. On an aptamer modified electrode, aptamer density was estimated to be about 4.4 × 10(12)molecules/cm(2). In IFN-γ studies, oxidation peak currents were found to decrease and more than 50% signal suppression was achieved at 500 ng/ml. Further, the magnitude of signal suppression was found to be logarithmically proportional to the IFN-γ in the concentration range of 1-500 ng/ml, with a detection limit of 1.3 ng/ml (i.e. 0.8 fmol in used sample volume of 10 µl). Biosensor showed negligible signal changes (5%) in a very high non-specific protein background, while still able to differentiate target protein IFN-γ at 5 ng/ml. The results indicated that our sensor binds selectively to target molecules, and the non-specific binding where adsorption of BSA protein molecules may be effectively omitted from consideration.

IFN-gamma alters the human sperm membrane permeability to Ca(2+)

Inflammation in the male genitourinary tract has been associated with the release of pro-inflammatory cytokines such as interferon-gamma (IFN-γ) and elevated reactive oxygen species, which affects spermatozoa capacitation, motility, and the acrosome reaction, along with functions regulated by the concentration of cytoplasmic Ca(2+) ([Ca(2+)]cyto). Though Ca(2+) signaling is of particular significance in sperm, the effect of IFN-γ intracellular calcium on these cells is still unknown. The present study evaluated the effect of IFN-γ on the [Ca(2+)]cyto and Ca(2+) permeability on human sperm. A cell suspension loaded with fura-2 was incubated with or without IFN-γ (from 0 to 2000 pg/ml) for 0, 30, 60, and 120 minutes, and the [Ca(2+)]cyto was measured. The permeability to Ca(2+) was evaluated by the change of the intracellular concentration following an extracellular Ca(2+) pulse. IFN-γ at low concentrations (≤ 500  pg/ml) did not affect the [Ca(2+)]cyto and Ca(2+) permeability of sperm. At a high concentration (2000  pg/ml), IFN-γ did not alter the [Ca(2+)](cyto), but significantly decreased the magnitude and velocity of Ca(2+) entry into the cell. This effect was dependent on incubation time and IFN-γ concentration. This alteration induced by IFN-γ was prevented by the simultaneous incubation of sperm with the antioxidant butylhydroxytoluene (BHT). In conclusion, in vitro, IFN-γ modifies Ca(2+) sperm membrane permeability, probably via lipid peroxidation. IFN-γ in high concentration, as observed in inflammation/infection, can affect [Ca(2+)](cyto) regulation and alter sperm fertilizing capacity.

17β-Estradiol and interferon tau interact in the regulation of the immune response in a model of experimental autoimmune orchitis

Immunoregulatory activity of type I interferons (IFNs) and estrogen is convergent in some cases of autoimmune disorders. The aim of our study was to determine whether a potent interaction of IFN and estradiol (E2) has an influence on immune response and estrogen receptor alpha (ER-?) expression in antigen-presenting cells in a model of experimental autoimmune orchitis (EAO). C3H/He/W male mice were immunized with testicular germ cells (TGCs) and orally treated with interferon tau (IFN-?), E2, or both simultaneously. The delayed-type hypersensitivity reaction was intensified after the administration of either IFN-? or E2, but their co-administration had no effect. IFN-? treatment increased immunoglobulin G2a (IgG2a) and decreased IgG1 levels of TGC-specific antibodies, whereas E2 abolished the effects of the used cytokine. The total splenic cellularity and the number of spleen CD11c+MHC II+ and F4/80+MHC II? cells were increased after IFN-? treatment, whereas E2 antagonized this effect. After IFN-? administration the level of ER-? was significantly higher in F4/80+MHC II? cells, whereas E2 had no effect. However, the administration of E2 significantly reduced the ER-? level in F4/80+MHC II+ and CD11c+MHC II+ cells in comparison with the IFN-??treated groups. In the EAO model, the type I IFN and E2 cooperated at the general and cellular levels of immune response, but E2 treatment usually abolished the effects exerted by the cytokine.

Intratesticular expression of mRNAs of both interferon γ and tumor necrosis factor α is significantly increased in experimental autoimmune orchitis in mice

Experimental autoimmune orchitis (EAO) is one of the models of immunological male infertility. Murine EAO is CD4+T cell-dependent and classically induced by immunization with a testicular homogenate and adjuvants. We previously established that immunization with viable syngeneic testicular germ cells (TGC) can also induce murine EAO with no use of any adjuvant. Analyses of this EAO model have already revealed that cultured spleen cells of immunized mice secreted interferon (IFN)-γ and that treatment of the immunized mice with anti-IFN-γ monoclonal antibodies significantly suppressed the EAO. It is known that both IFN-γ and tumor necrosis factor (TNF)-α are representative cytokines of Th1 cells and exhibit local toxicity toward the seminiferous epithelium in vivo. However, changes in these two cytokines in EAO-affected testes have not yet been investigated. Therefore, in the present study, we investigated the expression of intratesticular IFN-γ and TNF- α mRNAs in TGC-induced EAO using real-time RT-PCR. The results demonstrated that the intratesticular mRNAs for both IFN-γ and TNF-α significantly increased, while other cytokines such as IL-1α, IL-1β, IL-6 and TGF-β did not show dramatic changes in the immunized mice. These results suggest that secretion of significant amounts of IFN-γ and TNF-α in situ contributes to the spermatogenic disturbance in EAO.

CD4+ and CD8+ T cells producing Th1 and Th17 cytokines are involved in the pathogenesis of autoimmune orchitis

Experimental autoimmune orchitis (EAO) is a useful model to study chronic testicular inflammation and infertility. EAO is characterized by severe damage of seminiferous tubules with germ cells that undergo apoptosis and sloughing. We previously reported an increase in CD4+ and CD8+ effector T cells in the testes of rats with EAO. Since cytokine patterns determine T cell effector functions, in the present work we analyzed the cytokines expressed by these cells during disease development. By flow cytometry, we detected an increase in the number of tumor necrosis factor-α (TNF) and interferon -γ (IFNG)-producing CD4+ T cells in the testis at EAO onset. As the severity of the disease progressed, these cells declined while CD8+ T cells producing TNF and IFNG increased, with the predominance of IFNG expression. As a novel finding, we identified by immunofluorescence CD4+ interleukin 17 (IL17)+ and CD8+ IL17+ cells in the testes of EAO rats, with CD4+ and CD8+ T cells predominating at the onset and in the chronic phase of EAO respectively. Moreover, IL17 (western blot) and IL23 content (ELISA) increased in EAO, with maximum levels in the chronic phase. These results suggest the involvement of CD4+ T helper (Th) 1 and Th17 subsets as co-effector cells governing EAO onset, as well as the central contribution of CD8+ T cells producing Th1 and Th17 cytokines in the maintenance of chronic inflammation. The expression of T-bet and RORγt (western blot) in the testis over the course of disease also supports the presence of Th1 and Th17 cells in the testes of EAO rats.

Anticytokine therapy, particularly anti-IFN-gamma, in Th1-mediated autoimmune diseases

Anticytokine therapy was proposed in 1974 in Nature, in which it was stated that hyperproduced interferon can cause autoimmune disease and anti-interferon can be therapeutic. In 1989, the use of antibodies to tumor necrosis factor-alpha in combination with antibodies to certain types of interferon was proposed to treat various autoimmune diseases, including AIDS. The first anticytokine therapy was conducted in 1975. Anti-interferon-gamma has brought improved and often striking results in the treatment of various T-helper 1-mediated autoimmune diseases, including inflammatory skin diseases. Anti-interferon-gamma may be a universal treatment for these conditions. In AIDS and other virus-induced autoimmune diseases, the virus may stimulate cytokines (interferons), which increase, rather than halt, viral replication. Tumor necrosis factor-alpha inhibitors have also shown good clinical results, however, they may result in complications and are ineffective in some autoimmune diseases.

Immunology of the Testis and Male Reproductive Tract

A large body of evidence points to the existence of a close, dynamic relationship between the immune system and the male reproductive tract, which has important implications for our understanding of both systems. The testis and the male reproductive tract provide an environment that protects the otherwise highly immunogenic spermatogenic cells and sperm from immunological attack. At the same time, secretions of the testis, including androgens, influence the development and mature functions of the immune system. Activation of the immune system has negative effects on both androgen and sperm production, so that systemic or local infection and inflammation compromise male fertility. The mechanisms underlying these interactions have begun to receive the attention from reproductive biologists and immunologists that they deserve, but many crucial details remain to be uncovered. A complete picture of male reproductive tract function and its response to toxic agents is contingent upon continued exploration of these interactions and the mechanisms involved.

Cytokines and chemokines in testicular inflammation: A brief review

A wide spectrum of data in the literature shows the relevance of cytokines as paracrine regulators of spermatogenesis and steroidogenesis in the normal testis. In this brief review, we highlight the relevance of cytokines in the testis during inflammation. This phenomenon involves complex and multiple interactions among immune and germ cells generally resulting in the alteration of spermatogenesis. The complexity of these cell interactions is multiplied because Sertoli and Leydig cells are also producers of pro- and anti-inflammatory cytokines and chemokines. Also, cytokines are pleiotropic and they exert opposite and/or redundant effects in different conditions. However, in spite of this bidirectional immunoregulatory function of cytokines, the mass of the data, reported from experiments of acute testicular inflammation, shows upregulation of interleukin (IL)-1beta, IL-1alpha, IL-6, and tumor necrosis factor alpha (TNF-alpha), which induce adverse effects on germ cells. In autoimmune orchitis, a chronic testicular inflammation, chemokines such as CCL2, CCL3, and CCL4 induce attraction and extravasation of immune cells within the testicular interstitium. These cells alter the normal immunosuppressor microenvironment principally through the secretion of proinflammatory cytokines, interferon-gamma initially, and IL-6 and TNF-alpha thereafter. Germ cells expressing TNFR1, IL-6R, and Fas increase in number and undergo apoptosis, through the TNF-alpha/TNFR1, IL-6/IL-6R, and Fas/Fas L systems. The knowledge of immune-germ and somatic testicular cell interactions will contribute to the understanding of the mechanisms by which chronic inflammatory conditions of the testis can disrupt the process of spermatogenesis.

Splenic cytokines in mice immunized with testicular germ cells

We previously established that two subcutaneous injections of viable syngeneic testicular germ cells (TGC) alone can induce CD4+ T cell-dependent experimental autoimmune orchitis (EAO) in mice. This model is histologically characterized by lymphocytic infiltration into the testes and the following aspermatogenesis. In the present study, we investigated the dynamics of splenic cytokines in EAO, using specific enzyme-linked immunosorbent assay. We found that splenic production of both type 1 helper T cell (Th1) and type 2 helper T cell (Th2)-related cytokines increased after the second but not the first immunization with TGC, indicating that secondary immune responses are critical to the EAO induction. However, the production of Th1-related cytokines became predominant at the clinical stage of EAO. Additionally, serum FSH and inhibin-B increased and decreased, respectively, during EAO. On the other hand, LH did not significantly change and testosterone temporally increased during the same period. These results indicate that both Th1- and Th2-related cytokines are involved at the pre-clinical phase of EAO, but that Th1- rather than Th2-related cytokines are responsible for the clinical phase when spermatogenesis is disrupted but the Leydig cell function is well preserved.

Mutual antagonistic relationship between prostaglandin E(2) and IFN-gamma: Implications for rheumatoid arthritis

Prostaglandin E(2) (PGE(2)) is a major mediator of inflammation and is present at high concentrations in the synovial fluid of rheumatoid arthritis (RA) patients. PGE(2), acting through the EP4 receptor, has both pro- and anti-inflammatory roles in vivo. To shed light on this dual role of PGE(2), we investigated its effects in whole blood and in primary human fibroblast-like synoviocytes (FLS). Gene expression analysis in human leukocytes, confirmed at the protein level, revealed an EP4-dependent inhibition of the expression of genes involved in the IFN-gamma-activation pathway, including IFN-gamma itself. This effect of the PGE(2)/EP4 axis on IFN-gamma is a reciprocal phenomenon since IFN-gamma blocks PGE(2) release and blocks EP receptor expression. The mutually antagonistic relationship between IFN-gamma and PGE(2) extends to downstream cytokine and chemokine release; PGE(2) counters the effects of IFN-gamma, on the release of IP-10, IL-8, TNF-alpha and IL-1beta. To gain further insight into IFN-gamma-mediated cellular events in RA, we assessed the effects of IFN-gamma on gene expression in FLS. We observed an IFN-gamma-dependent up-regulation of macrophage-attracting chemokines, and down-regulation of metalloprotease expression. These results suggest the existence of a mutually antagonistic relationship between PGE(2) and IFN-gamma, which may represent a fundamental mechanism of immune control in diseases such as RA.

Tumour necrosis factor-alpha released by testicular macrophages induces apoptosis of germ cells in autoimmune orchitis

BACKGROUND

Experimental autoimmune orchitis (EAO) is a model of chronic inflammation and infertility useful for studying testicular immune and germ cell (GC) interactions. In this model, EAO was induced in rats by immunization with testicular homogenate and adjuvants; Control (C) rats were injected with adjuvants. EAO was characterized by an interstitial infiltrate of lymphomonocytes and seminiferous tubule damage, moderate 50 days (focal orchitis) and severe 80 days after the first immunization (severe orchitis). Based on the previous results showing that the number of macrophages and apoptotic GC expressing tumour necrosis factor (TNF) receptor 1 increased in EAO, we studied the role of macrophages and TNF-alpha in GC apoptosis.

METHODS AND RESULTS

Conditioned media of testicular macrophages (CMTM) obtained from rats killed on Days 50 and 80 decreased the viability (MTS, P < 0.01) and induced apoptosis (terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labelling, TUNEL) of GC obtained from EAO but not from non-immunized, N rats (P < 0.001). TNF-alpha content (enzyme-linked immunosorbent assay) was significantly higher in the CMTM from EAO versus C rats on Day 80 (P < 0.05). The apoptotic effect of CMTM from Day 80 rats was abrogated by a selective TNF-alpha blocker (Etanercept). Moreover, TNF-alpha in vitro induced GC apoptosis. TNF-alpha expression (by immunofluorescence) was observed in testicular (ED2(+)) and non-resident (ED1(+)) macrophages, the percentage of TNF-alpha(+) macrophages being similar in focal and severe orchitis.

CONCLUSIONS

Results demonstrated that soluble factors released from testicular EAO macrophages induce apoptosis of GC, biased by the local inflammatory environment, and that TNF-alpha is a relevant cytokine involved in testicular damage during severe orchitis.

The pro- and anti-inflammatory potential of IL-12: the dual role of Th1 cells

The differentiation of T-helper (Th) lymphocytes into various types of T-helper effector and memory cells with distinct functions depending on the type of concomitant signals they receive upon activation is a critical event determining the course of an immune reaction. Th1 cells characterized by the expression of IFN-gamma and the recently described Th17 cells promote inflammation and are critically involved in the induction and maintenance of autoimmunity, whereas the secretion of IL-4 is a hallmark of Th2 cells mediating protection from parasites and allergy. Original stimulation in the presence of IL-12 results in the imprinting of Th1 memory cells for the expression of IFN-gamma by expression of the transcription factor T-bet and epigenetic modification of the ifngamma gene. It has been demonstrated that Th1 cells are potent inducers of inflammation. However, in the chronic phase of such inflammation, the regulatory potential of IL-12 and Th1 cells themselves may play an important role in limiting immunopathology.

Anticytokine therapy, especially anti-interferon-gamma, as a pathogenetic treatment in TH-1 autoimmune diseases

We pioneered anticytokine therapy (ACT) in 1974 and 1989, proposing to remove interferon (IFN) and tumor necrosis factor (TNF)-alpha together with IFNs to treat various autoimmune diseases, including AIDS. This hypothesis was confirmed in different laboratories and opened a new line to produce and test different anticytokines. We have had good, sometimes striking results treating various Th1-mediated autoimmune diseases, including inflammatory skin diseases, using anti-IFN-gamma and sometimes anti-TNF-alpha. Anti-IFN-gamma may be a universal treatment for these conditions. Because TNF-alpha inhibitors, now successfully used in certain autoimmune disorders, have many severe side effects, there are opportunities for the development of other ACT and TNF-alpha antagonists with fewer side effects.

Adeno-associated virus-mediated human IL-10 gene transfer suppresses the development of experimental autoimmune orchitis

Testicular germ cell-induced autoimmune orchitis is characterized by inflammatory cell infiltration followed by disturbance of spermatogenesis. Experimental autoimmune orchitis (EAO) is an animal model for human immunological male infertility; delayed-type hypersensitivity (DTH) response plays a key role in its induction. Interleukin-10 (IL-10) is a regulatory cytokine that is critical in preventing organ-specific autoimmune inflammation. To determine the effects on EAO of human IL-10 (hIL-10) gene transfer, C3H/He mice immunized by unilateral testicular injury were administered intramuscular (i.m.) injections of adeno-associated viral (AAV) vector-encoding hIL-10 on the day of immunization. Serum hIL-10 was detected beginning at 1 week postinjection, and peaked at 3 weeks. Histological examinations showed a significantly low incidence of orchitis and disturbance of spermatogenesis in AAV hIL-10-treated mice, and the DTH response to autologous testicular cells was significantly suppressed. Immunohistochemical analysis of IFN- and IL-2, T-cell-associated cytokines, in the spleen and testes revealed significantly fewer cytokine-expressing cells after treatment. We conclude that a single i.m. administration of AAV hIL-10 significantly suppresses EAO and hypospermatogenesis by regulating cell-mediated immunity in the testes.

Tissue microcircumstances for leukocytic infiltration into the testis and epididymis in mice

Spermatozoa do not appear in the seminiferous epithelium until puberty, when immune tolerance has already been established. Therefore, they contain various autoimmunogenic materials which are recognized as foreign by the self immune system. However, the testis and epididymis are known as immunologically privileged organs. In particular, the blood-testis barrier (BTB) formed by Sertoli cells and the blood-epididymal barrier formed by epididymal epithelial cells protect autoimmunogeneic spermatozoa from attack by the self immune system. The immune privileged circumstances in the testis and epididymis have been demonstrated by many studies to involve a local transplantation system. We review here the immune privileged status of these organs from the viewpoint of induction of inflammatory cell responses in mice. The testicular interstitium in mice is resistant to vasculitis, lymphangitis, spermatic granuloma and polymorphonuclear cell infiltration: however, the epididymal interstitium is vulnerable to them. Therefore, the testicular tissue outside BTB is also protected from inflammatory cell infiltration, although many resident macrophages are normally present in the testis. In sharp contrast, subcutaneous injection of viable syngeneic testicular germ cells (TGC) alone induces autoimmune orchitis with no involvement of the epididymitis in mice. In the testes of TGC-immunized animals, severe lymphocytic infiltration with aspermatogenesis was seen in spite of no use of adjuvants. Unexpectedly, injections of viable epididymal spermatozoa (ES) did not evoke any autoimmune inflammation in the epididymides. Therefore, the testis rather than the epididymis may easily become an unprivileged organ as to autoimmunity under some special conditions.

Proinflammatory effects of exogenously administered IL-10 in experimental autoimmune orchitis

We studied the effects of exogenously administered recombinant murine interleukin (IL)-10 on the development of experimental autoimmune orchitis (EAO) in C3H/He mice. IL-10 significantly augments histological signs of EAO when administered for 6 consecutive days from days 15 to 20 after primary immunisations with testicular germ cells. These data demonstrate that IL-10, in addition to its well-known antiinflammatory property, also has proinflammatory functions capable of up-regulating testicular immunoinflammatory processes in vivo.

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.

Short-term prophylaxis with deoxyspergualin prevents testicular autoimmunity in mice

The effects of the treatment with the immunosuppressant deoxyspergualin on the development of experimental autoimmune orchitis were studied. The results showed that C3H/He mice immunized with testicular germ cells and treated daily with either 0.3 or 3 mg/kg body weight deoxyspergualin during days 15-20 post-immunization developed experimental autoimmune orchitis lesions with a significantly lower incidence and severity than did the control mice treated under the same experimental conditions with phosphate buffered saline (PBS). The effects of deoxyspergualin were clearly dose-dependent, and the higher dose of the drug also markedly reduced the degree of delayed type hypersensitivity responses against testicular germ cells. These data suggest that deoxyspergualin may be worthy of consideration for the prevention/treatment of human immunoinflammatory orchitis.

Reexamination of the difference in susceptibility to adjuvant-induced arthritis among LEW/Crj, Slc/Wistar/ST and Slc/SD rats

The present investigations were performed to assess the differences among rat colonies commonly used for neurophysiological research regarding the development of complete Freund's adjuvant (CFA)-induced arthritis. Inflammatory signs including edema in the paw fluctuated remarkably among individual Wistar (Slc/Wistar/ST) and Sprague-Dawley (Slc/SD) rats, while the inflammatory signs of Lewis (LEW/Crj) rats appeared earlier and was severer and more consistent than Slc/Wistar/ST and Slc/SD rats. Edema in the hind paw developed in 100% of LEW/Crj rats with the lowest dose of CFA (0.6 mg/rat) used as compared with 64% of Slc/Wistar/ST (CFA 1 mg/rat) and 38% of Slc/SD rats (CFA 1.2 mg/rat). Retardation of weight gain was observed in Slc/Wistar/ST and Slc/SD rats in contrast to a severe weight decrease in inflamed LEW/Crj rats after the development of arthritis.

Prevention of murine experimental autoimmune orchitis by recombinant human interleukin-6

We studied the effect of exogenously administered recombinant human interleukin (IL)-6 on the development of experimental autoimmune orchitis (EAO) in C3H/Hej mice. IL-6 significantly reduced histological signs of EAO and appearance of delayed type hypersensitivity against the immunizing testicular germinal cells. The effect was seen even though the cytokine was administered for only 6 consecutive days and 2 weeks after immunization.

Mac-1(+) myelopoiesis induced by CFA: a clue to the paradoxical effects of IFN-gamma in autoimmune disease models

The mechanisms accounting for the protective role of endogenous interferon gamma (IFN-gamma) in certain murine autoimmune disease models, versus a disease-promoting role in others, have remained elusive. The protective effect of IFN-gamma might be unique to models that rely on the use of complete Freund's adjuvant (CFA) and whose pathogenesis is predominantly driven by delayed-type hypersensitivity. In these models, IFN-gamma counteracts disease development by inhibiting CFA-induced proliferation of a pathogenically important Mac-1(+) cell population(s). This calls into question our usual conceptualization of the balance between innate and specific immunity in these models, as well as their clinical relevance, particularly when the role of IFN-gamma or related cytokines is considered.

Susceptibility to collagen-induced arthritis: cytokine-mediated regulation

Collagen-induced arthritis is an animal model of inflammatory polyarthritis that is induced in susceptible strains of rats and mice by intradermal immunization with heterologous type II collagen emulsified in complete Freund's adjuvant. Previous studies have demonstrated that disease induction is highly MHC-restricted, with only mice of H-2(q) or H-2(r) haplotypes being susceptible. We have used a panel of both susceptible and resistant strains of mice in which either IFN-gamma or IL-10 signaling has been abolished by gene deletion and show that disease can be readily induced in several resistant strains of the H-2(b) and H-2(d) haplotype; susceptibility was highly dependent on IL-12. IL-4 was also shown to be crucial for disease induction in this model. These results suggest that both Th1 and Th2 cytokines may be important in the etiopathogenesis of disease and that disease susceptibility may be a function of a dysregulated cytokine environment.

Murine concanavalin A-induced hepatitis is prevented by interleukin 12 (IL-12) antibody and exacerbated by exogenous IL-12 through an interferon-gamma-dependent mechanism

Concanavalin A (ConA)-induced hepatitis is a cell-mediated immunoinflammatory condition similar to human autoimmune hepatitis. We investigated the role of interleukin 12 (IL-12) in hepatitis induced in NMRI and C57/BL6 mice by a single injection of ConA. Recombinant murine IL-12 administered 24 hours and 1 hour prior to ConA exacerbated both transaminase activities in plasma and histologic signs of hepatitis. These markers of liver injury were significantly reduced by prophylactic, but not therapeutic treatment with anti-IL-12 monoclonal antibody (mAb). The disease-modulatory effects of IL-12 and anti-IL-12 mAb were associated with profound and reverse modifications of a ConA-induced increase in the circulating levels of IL-4, IL-6, interferon gamma (IFN-gamma) and tumor necrosis factor (TNF). Relative to control animals receiving ConA alone, the plasma levels of these cytokines were all augmented in IL-12/ConA-treated mice and diminished in anti-IL-12 mAb/ConA-treated mice. Anti-IFN-gamma mAb also impeded the appearance of IL-12/ConA-induced hepatitis. Thus, IL-12-induced production of IFN-gamma might play a role in mediating the hepatitis-inducing effect of ConA. However, IL-12p40-deficient C57/BL6 mice were as susceptible as wild-type controls to the hepatitis-inducing effect of ConA.

Essential pathogenetic role for interferon (IFN-)gamma in concanavalin A-induced T cell-dependent hepatitis: exacerbation by exogenous IFN-gamma and prevention by IFN-gamma receptor-immunoglobulin fusion protein

We have studied the effects of either exogenously-administered interferon (IFN-)gamma or of a nonimmunogenic mouse IFN-gamma receptor-Immunoglobulin (IFN-gamma R-Ig) fusion protein on the development of Concanavalin (Con)A-induced hepatitis in NMRI mice. PBS-treated control mice injected with 20 mg/kg ConA developed classical serological and histological signs of hepatitis with elevation of transaminases in the blood and infiltration of the liver by mononuclear cells and neutrophils. Treating the mice with rat IFN-gamma 24 h prior to and 1 h after ConA-challenge markedly exacerbated these signs of hepatitis in a dose-dependent fashion. Moreover, mice injected with lower, non hepatitogenic, doses of ConA (10, 5 mg/kg) became fully susceptible to develop hepatitis upon similar treatment with IFN-gamma. Concordantly, ConA-induced hepatitis was abrogated by either IFN-gamma R-Ig fusion protein or anti-IFN-gamma mAb. These data provide further evidence for the central pathogenetic role of endogenous IFN-gamma in ConA-induced hepatitis and demonstrate the feasibility to prevent disease development by means of a non immunogenic IFN-gamma R-Ig fusion protein.

Enhanced Autoimmune Arthritis in IFN-γ Receptor-Deficient Mice Is Conditioned by Mycobacteria in Freund’s Adjuvant and by Increased Expansion of Mac-1+ Myeloid Cells

Induction of experimental autoimmune diseases often relies on immunization with the organ-specific autoantigens in CFA, which contains heat-killed mycobacteria. In several of these models, including collagen-induced arthritis, endogenous IFN-γ acts as a disease-limiting factor in the pathogenesis of the disease. Here we show that in collagen-induced arthritis the protective effect of IFN-γ depends on the presence of mycobacteria in the adjuvant. Omission of mycobacteria inverts the role of endogenous IFN-γ to a disease-promoting factor. Thus, the mycobacterial component of CFA opens a pathway by which endogenous IFN-γ exerts a protective effect that supersedes its otherwise disease-promoting effect. Extramedullary hemopoiesis and expansion of the Mac-1+ cell population accompanied the accelerated and more severe disease course in the IFN-γ receptor knockout mice immunized with CFA. Treatment of such mice with Abs against the myelopoietic cytokines IL-6 or IL-12 inhibited both disease development and the expansion of the Mac-1+ population. We postulate that mycobacteria in CFA stimulate the expansion of the Mac-1+ cell population by a hemopoietic process that is restrained by endogenous IFN-γ. These results have important implications for the validity of animal models of autoimmunity to study the pathogenesis and to evaluate cytokine-based therapy of autoimmune diseases.

Role of cytokines in testicular function

Inflammatory disease has been established to affect male reproductive function and fertility. Relevant inflammatory diseases include general and chronic infectious diseases as well as localized acute or chronic infections of the male genitourinary tract. Male accessory gland infections account for almost 15% of all cases of male infertility seen in infertility clinics while fertility usually is not a clinical objective among patients with acute systemic infections such as Gram-negative sepsis. Infections of the male accessory glands frequently are associated with increased counts of white blood cells in semen and elevated levels of proinflammatory cytokines in semen and the testis. There is a mounting body of evidence that demonstrates the importance of cytokines and chemokines in the regulation of testicular and glandular function during pathophysiological states as well as under normal physiological conditions when cytokines act as growth and differentiation factors. The purpose of this review is to examine the role of cytokines in the regulation of steroidogenesis and spermatogenesis in the testis under physiological and pathophysiological conditions and considers clinical investigations that help to improve the evaluation and treatment of male infertility.