Exacerbation of delayed-type hypersensitivity responses in EBV-induced gene-3 (EBI-3)-deficient mice

Peripheral blood mononuclear cell transcriptome profile in a clinical trial with subcutaneous, grass pollen allergoid immunotherapy

INTRODUCTION

Allergen-specific immunotherapy (AIT) is the only disease-modifying treatment in allergic airway diseases. Underlying immunological mechanisms and candidate biomarkers, which may be translated into predictive/surrogate measures of clinical efficacy, remain an active area of research. The aim of this study was to evaluate Pollinex Quattro (PQ) Grass AIT induced immunomodulatory mechanisms, based on transcriptome profiling of peripheral blood mononuclear cells.

METHODS

119 subjects with grass pollen induced seasonal allergic rhinitis (SAR) were randomized in a 2:2:1:1 ratio to receive a cumulative dose of PQ Grass as a conventional or extended pre-seasonal regimen, placebo, or placebo with MicroCrystalline Tyrosine. Gene expression analysis was an exploratory endpoint evaluated in a subgroup of 30 subjects randomly selected from the four treatment arms. Samples were collected at three time points: screening (baseline), before the start of the grass pollen season and at the end of the season. This study was funded by the manufacturer of PQ.

RESULTS

Transcriptome analysis demonstrated that the most significant changes in gene expression, for both treatment regimens, were at the end of the grass pollen season, with the main Th1 candidate molecules (IL-12A, IFNγ) upregulated and Th2 signature cytokines downregulated (IL-4, IL-13, IL-9) (p < .05). Canonical pathways analysis demonstrated Th1, Th2, Th17 and IL-17 as the most significantly enriched pathways based on absolute value of activation z-score (IzI score ≥ 2, p < .05). Upstream regulator analysis showed pronounced inhibition of pro-inflammatory allergic molecules IgE, IL-17A, IL-17F, IL-25 (IL-17E) (IzI score ≥ 2, FDR < 0.05) and activation of pro-tolerogenic molecules IL-12A, IL-27, IL-35 (EBI3) at the end of the grass pollen season.

CONCLUSION

Peripheral blood mononuclear cells transcriptome profile showed an inhibition of Th2, Th17 pro-inflammatory allergic responses and immune deviation towards Th1 responses. PQ Grass extended regimen exhibited a superior mechanistic efficacy profile in comparison with PQ conventional regimen.

IL-27 Derived From Macrophages Facilitates IL-15 Production and T Cell Maintenance Following Allergic Hypersensitivity Responses

Crosstalk between T cells, dendritic cells, and macrophages in temporal leukocyte clusters within barrier tissues provides a new concept for T cell activation in the skin. Activated T cells from these leukocyte clusters play critical roles in the efferent phase of allergic contact hypersensitivity (CHS). However, the cytokines driving maintenance and survival of pathogenic T cells during and following CHS remain mostly unknown. Upon epicutaneous allergen challenge, we here report that macrophages produce IL-27 which then induces IL-15 production from epidermal keratinocytes and dermal myeloid cells within leukocyte clusters. In agreement with the known role of IL-15 as a T cell survival factor and growth cytokine, this signaling axis enhances BCL2 and survival of skin T cells. Genetic depletion or pharmacological blockade of IL-27 in CHS mice leads to abrogated epidermal IL-15 production resulting in a decrease in BCL2 expression in T cells and a decline in dermal CD8⁺ T cells and T cell cluster numbers. These findings suggest that the IL-27 pathway is an important cytokine for regulating cutaneous T cell immunity.

Fermented food Tempeh induces interleukin 12 and enhances macrophage phagocytosis

It is known that lactic acid bacteria induce the IL-12. The IL-12 activates NK cells and promotes the production of IFN-γ. The IFN-γ activates macrophages resulting in enhanced phagocytosis and bactericidal activity. We have been investigating fermented foods that activate the immune function. In this study, we investigated the IL-12 inducibility of fermented foods using the specific antibody. Fermented soybean foods such as Tempeh and Natto are attracting attention in terms of nutrition, functionality, and food problems. In this study, Tempeh induced 1,080 µg/ml of IL-12, and IFN-γ associated with the induction of IL-12 was also induced at 682 µg/ml. This was more than twice the induced intensity of PBS. On the contrary, Natto hardly induced IL-12 and IFN-γ. Tempeh also accelerated phagocytosis of the macrophage THP-1 cells. In this study, it was found that the fermented soybean-derived food, Tempeh, has a function of activating the immune function. This is the first report that Tempeh activates innate immunity. PRACTICAL APPLICATIONS: Tempeh, a fermented soybean food induced the IL-12 and IFN-γ production and the increase of macrophage phagocytosis in this study suggested a new function to enhance immunity. Tempeh is also expected to be effective in preventing lifestyle diseases. Fermented soybean products of Tempeh was considered to be a very useful health food for the problems of modern society such as maintaining health by eating, improving immunity, and ingesting vegetable protein due to diversifying food.

Different expression levels of interleukin-35 in asthma phenotypes

Background

Interleukin (IL)-35 is a newly discovered inhibitory cytokine which is produced by regulatory B and T lymphocytes and belongs to the IL-12 family. It plays a suppressive role in human inflammatory diseases; however, its role in asthma phenotypes is unclear. Our study focuses on the sputum IL-35 level in patients and investigates different airway inflammation capacities of sputum IL-35 in patients with different asthma phenotypes.

Objective

We aimed to determine the sputum IL-35 levels in asthmatic patients with clinical remission phenotypes and control subjects and to investigate possible correlations among lung function, age, sex, fractional exhaled nitric oxide (FeNO), and smoking history in these phenotypes.

Methods

Sputum samples were collected from patients with clinical asthma remission (n = 89, 37 males, age 52.24 ± 13.32 years) and a healthy control group (n = 19, 9 males, age 44.58 ± 16.3 years). All subjects underwent sputum induction. Induced sputum was assessed for inflammatory cell count, and sputum levels of IL-35 and other cytokines were measured by ELISA and Cytometric Bead Array, respectively.

Results

Sputum IL-35 (median (q1, q3)) levels showed no significant difference between asthma patients (4.89 ng/mL (2.97, 22.75)) and healthy controls (6.01 ng/mL (4.09, 30.47)). However, the sputum IL-35 level was significantly reduced in patients with eosinophilic asthma (EA) (3.95 ng/mL (2.80, 11.00)) compared to patients with neutrophilic asthma (NA) (40.59 ng/mL (20.59, 65.06), p = 0.002), paucigranulocytic asthma (PA) (6.25 ng/mL (3.10, 24.60), p = 0.012), and mixed granulocytic asthma (MA) (22.54 ng/mL (2.58, 52.45), p = 0.026). IL-35 levels in sputum showed a positive correlation with sputum neutrophil cells and a negative correlation with FeNO, FEV1% predicted, and FVC predicted. Furthermore, sputum IL-35 had a significant positive association with Th1-related factors and a negative correlation with Th2-related factors.

Conclusions

Sputum IL-35 is likely involved in different pathophysiological mechanisms of NA and EA and exerts different effects in asthma phenotypes.

Schistosoma japonicum peptide SJMHE1 suppresses airway inflammation of allergic asthma in mice

Helminths and their products can shape immune responses by modulating immune cells, which are dysfunctional in inflammatory diseases such as asthma. We previously identified SJMHE1, a small molecule peptide from the HSP60 protein of Schistosoma japonicum. SJMHE1 can inhibit delayed-type hypersensitivity and collagen-induced arthritis in mice. In the present study, we evaluated this peptide's potential intervention effect and mechanism on ovalbumin-induced asthma in mice. SJMHE1 treatment suppressed airway inflammation in allergic mice, decreased the infiltrating inflammatory cells in the lungs and bronchoalveolar lavage fluid, modulated the production of pro-inflammatory and anti-inflammatory cytokines in the splenocytes and lungs of allergic mice, reduced the percentage of Th2 cells and increased the proportion of Th1 and regulatory T cells (Tregs). At the same time, Foxp3 and T-bet expression increased, and GATA3 and RORγt decreased in the lungs of allergic mice. We proved that SJMHE1 can interrupt the development of asthma by diminishing airway inflammation in mice. The down-regulation of Th2 response and the up-regulation of Th1 and Tregs response may contribute to the protection induced by SJMHE1 in allergic mice. SJMHE1 can serve as a novel therapy for asthma and other allergic or inflammatory diseases.

Role of IL-35 in sublingual allergen immunotherapy

BACKGROUND

Grass pollen-specific immunotherapy involves immunomodulation of allergen-specific T_H2 responses and induction of IL-10⁺ and/or TGF-β⁺CD4⁺CD25⁺ regulatory T cells (induced Treg cells). IL-35⁺CD4⁺CD25⁺ forkhead box protein 3-negative T (IL-35-inducible regulatory T [iT_R35]) cells have been reported as a novel subset of induced Treg cells with modulatory characteristics.

OBJECTIVE

We sought to investigate mechanisms underlying the induction and maintenance of immunologic tolerance induced by IL-35 and iT_R35 cells.

METHODS

The biological effects of IL-35 were assessed on group 2 innate lymphoid cells (ILC2s); dendritic cells primed with thymic stromal lymphopoietin, IL-25, and IL-33; and B and T_H2 cells by using flow cytometry and quantitative RT-PCR. Grass pollen-driven T_H2 cell proliferation and cytokine production were measured by using tritiated thymidine and Luminex MagPix, respectively. iT_R35 cells were quantified in patients with grass pollen allergy (seasonal allergic rhinitis [SAR] group, n = 16), sublingual immunotherapy (SLIT)-treated patients (SLIT group, n = 16), and nonatopic control subjects (NACs; NAC group, n = 16).

RESULTS

The SAR group had increased proportions of ILC2s (P = .002) and IL-5⁺ cells (P = .042), IL-13⁺ cells (P = .042), and IL-5⁺IL-13⁺ ILC2s (P = .003) compared with NACs. IL-35 inhibited IL-5 and IL-13 production by ILC2s in the presence of IL-25 or IL-33 (P = .031) and allergen-driven T_H2 cytokines by effector T cells. IL-35 inhibited CD40 ligand-, IL-4-, and IL-21-mediated IgE production by B cells (P = .015), allergen-driven T-cell proliferation (P = .001), and T_H2 cytokine production mediated by primed dendritic cells. iT_R35 cells suppressed T_H2 cell proliferation and cytokine production. In addition, allergen-driven IL-35 levels and iT_R35 cell counts were increased in patients receiving SLIT (all, P < .001) and NACs (all, P < .001) compared with patients with SAR.

CONCLUSION

IL-35 and iT_R35 cells are potential novel immune regulators induced by SLIT. The clinical relevance of SLIT can be underscored by restoration of protective iT_R35 cells.

Apaf1 plays a negative regulatory role in T cell responses by suppressing activation of antigen-stimulated T cells

Apaf1 is a critical component of the apoptosome and initiates apoptosis downstream mitochondrial damages. Although the importance of Apaf1 in embryonic development was shown, the role of Apaf1 in immune responses, especially T cell responses, has yet to be elucidated. We generated T cell-specific Apaf1-deficient mice (Lck-Cre-Apaf1^f/f mice) and examined the antigen-specific delayed-type hypersensitivity (DTH). Lck-Cre-Apaf1^f/f mice exhibited exacerbation of DTH responses as compared with Apaf1-sufficient control mice. In Lck-Cre-Apaf1^f/f mice, antigen-specific T cells proliferated more, and produced more inflammatory cytokines than control T cells. Apaf1-deficient T cells from antigen-immunized mice showed higher percentages of activation phenotypes upon restimulation in vitro. Apaf1-deficient T cells from naive (non-immunized) mice also showed higher proliferation activity and cytokine production over control cells. The impact of Apaf1-deficiency in T cells, however, was not restored by a pan-caspase inhibitor, suggesting that the role of Apaf1 in T cell responses was caspase-independent/non-apoptotic. These data collectively demonstrated that Apaf1 is a negative regulator of T cell responses and implicated Apaf1 as a potential target for immunosuppressive drug discovery.

IL-35 Suppresses Lipopolysaccharide-Induced Airway Eosinophilia in EBI3-Deficient Mice

EBI3 functions as the subunit of immune-regulatory cytokines, such as IL-27 and IL-35, by pairing with p28 and p35, respectively. We treated wild-type and EBI3-deficient mice with intratracheal administration of LPS and obtained bronchoalveolar lavage fluid (BALF) 24 h later. Although neutrophils were the predominant cells in BALF from both groups of mice, eosinophils were highly enriched and there was increased production of eosinophil-attracting chemokines CCL11 and CCL24 in BALF of EBI3-deficient mice. The bronchial epithelial cells and alveolar macrophages were the major producers of CCL11 and CCL24. Because no such increases in eosinophils were seen in BALF of p28/IL-27-deficient mice or WSX-1/IL-27Rα subunit-deficient mice upon intratracheal stimulation with LPS, we considered that the lack of IL-35 was responsible for the enhanced airway eosinophilia in EBI3-deficient mice. In vitro, IL-35 potently suppressed production of CCL11 and CCL24 by human lung epithelial cell lines treated with TNF-α and IL-1β. IL-35 also suppressed phosphorylation of STAT1 and STAT3 and induced suppressor of cytokine signaling 3. In vivo, rIL-35 dramatically reduced LPS-induced airway eosinophilia in EBI3-deficient mice, with concomitant reduction of CCL11 and CCL24, whereas neutralization of IL-35 significantly increased airway eosinophils in LPS-treated wild-type mice. Collectively, our results suggest that IL-35 negatively regulates airway eosinophilia, at least in part by reducing the production of CCL11 and CCL24.

Interleukin (IL)-39 [IL-23p19/Epstein-Barr virus-induced 3 (Ebi3)] induces differentiation/expansion of neutrophils in lupus-prone mice

Interleukin (IL)-12 family cytokines play critical roles in autoimmune diseases. Our previous study has shown that IL-23p19 and Epstein-Barr virus-induced 3 (Ebi3) form a new IL-12 family heterodimer, IL-23p19/Ebi3, termed IL-39, and knock-down of p19 or Ebi3 reduced diseases by transferred GL7⁺ B cells in lupus-prone mice. In the present study, we explore further the possible effect of IL-39 on murine lupus. We found that IL-39 in vitro and in vivo induces differentiation and/or expansion of neutrophils. GL7⁺ B cells up-regulated neutrophils by secreting IL-39, whereas IL-39-deficient GL7⁺ B cells lost the capacity to up-regulate neutrophils in lupus-prone mice and homozygous CD19^cre (CD19-deficient) mice. Finally, we found that IL-39-induced neutrophils had a positive feedback on IL-39 expression in activated B cells by secreting B cell activation factor (BAFF). Taken together, our results suggest that IL-39 induces differentiation and/or expansion of neutrophils in lupus-prone mice.

High IL-35 pleural expression in patients with tuberculous pleural effusion

Background

IL-35 is a novel anti-inflammatory and immunosuppressive cytokine primarily produced by Treg cells, and is involved in inflammatory diseases and autoimmune diseases. However, its roles in tuberculous pleural effusion (TPE) remain unknown. We aimed to investigate the potential involvement of IL-35 in TPE.

Material/Methods

Thirty TPE patients and 20 lung cancer patients with malignant pleural effusion (MPE) were recruited. Samples of pleural effusion (100 mL) were collected after traditional pleurocentesis. Blood was sampled from TPE patients. Mononuclear cells were isolated by Ficoll-Hypaque gradient. Proportions of Th1, Th17, and IL-35-producing cells were analyzed by flow cytometry. IL-35 was assessed by real-time RT-PCR, ELISA, and immunofluorescence. An ELISPOT assay was used to assess the effect of IL-35 on pleural effusion mononuclear cells (PEMCs).

Results

Proportions of IL-35-producing cells were higher in TPE compared with MPE (49.4±6.0 vs. 15.8±5.4%, P<0.001) and blood from TPE patients (49.4±6.0% vs. 16.6±3.1, P<0.001). IL-35, IL-17 and IFN-γ were elevated in TPE compared with MPE (all P<0.01). ELISPOT assay showed that IL-35 reduced the proportion of IFN-γ-producing CD4⁺ T cells in TPE. IL-35 mRNA expression was higher in TPE compared with MPE (P<0.001). Immunofluorescence showed that IL-35-positive cells were present in pleural tissues from TPE patients.

Conclusions

Results suggest that there is an imbalance in IL-35 metabolism in TPE. However, further studies are required to assess the exact relationship with the immune system response to tuberculosis. IL-35 might play a role in TPE and might be targeted as a treatment for TPE.

Reduced IL-35 levels are associated with increased platelet aggregation and activation in patients with acute graft-versus-host disease after allogeneic hematopoietic stem cell transplantation

Acute graft-versus-host disease (aGVHD) is a major complication associated with allogeneic hematopoietic stem cell transplantation (allo-HSCT). Interleukin (IL)-35 is a novel anti-inflammatory cytokine that suppresses the immune response. This prospective study explored IL-35 plasma levels in 65 patients after HSCT. The results revealed that the peripheral blood of patients with grades III-IV aGVHD (23.46 ng/ml) had reduced IL-35 compared to transplanted patients with grades I-II aGVHD (40.26 ng/ml, p < 0.01) or patients without aGVHD (41.40 ng/ml, p < 0.05). Allografts, including granulocyte colony-stimulating factor (G-CSF)-mobilized peripheral blood progenitor cell (PBPC) and G-CSF-primed bone marrow (GBM), from 38 patients were analyzed for IL-35 levels with respect to aGVHD. The patients who received lower levels of IL-35 cells in the GBM (28.0 ng/ml, p = 0.551) or lower levels of IL-35 in PBPC (53.46 ng/ml, p = 0.03) exhibited a higher incidence of aGVHD. Patients with aGVHD have increased platelet aggregation. IL-35 was added to patient blood in vitro, and platelet aggregation was inhibited by IL-35 in a dose-dependent manner. The markers of platelet activation (CD62P/PAC-1) can also be inhibited by IL-35. The results indicate that IL-35 may affect the development of aGVHD by inhibiting platelet activation and aggregation. Our data suggests that IL-35 represents a potentially effective therapeutic agent against aGVHD after allo-HSCT.

Human interleukin-27: wide individual variation in plasma levels and complex inter-relationships with interleukin-17A

Although it is widely believed that interleukin (IL)-27 is anti-inflammatory, its role in controlling human immune responses is not fully established. In particular, its interactions with T helper type 17 (Th)17 cytokines are unclear. Our aims were to establish the relationships between IL-27 and proinflammatory cytokines, including IL-17A, in human sera and cultures of peripheral blood mononuclear cells. Plasma IL-27 levels in 879 healthy humans from 163 families varied widely, but with relatively low heritability (19%). Despite IL-27 including a subunit encoded by Epstein-Barr virus-induced gene 3 (EBI3), there was no correlation of levels with serological evidence of infection with the virus. Although IL-27 has been reported to inhibit IL-17A production, we demonstrated a strong positive correlation in sera, but lower correlations of IL-27 with other proinflammatory cytokines. We verified that IL-27 inhibited IL-17A production by human peripheral blood T cells in vitro, but not that it stimulated IL-10 secretion. Importantly, addition of IL-17A decreased IL-27 production by stimulated T cells but had the opposite effect on resting T cells. Together, these data suggest a model whereby IL-27 and IL-17A exerts complex reciprocal effects to boost inflammatory responses, but restrain resting cells to prevent inappropriate activation.

EBI3 is pivotal for the initiation of experimental autoimmune uveitis

Murine experimental autoimmune uveitis (EAU) is a model for human autoimmune uveitis, whose pathogenesis is caused by both Th1 and Th17 cell responses. Epstein-Barr virus-induced gene 3 (EBI3) is a component of the heterodimeric cytokines: interleukin (IL)-27 and IL-35. Although IL-27 was shown to initiate Th1 cell development, it is also recognized as a negative regulator of fully activated CD4+ T cells, including Th17 cells. Recently, IL-35 also has also been reported to play immunosuppressive roles in autoimmunity. To investigate the roles of EBI3 in EAU, EBI3(-/-) mice were immunized with human interphotoreceptor retinoid binding protein peptide 1-20 (IRBP) to induce EAU. We observed that the clinical score in EBI3(-/-) mice was diminished compared with that in EBI3(+/+) mice up to day 22 after immunization, whereas the score in EBI3(-/-) mice reached the same levels as that of EBI3(+/+) mice after day 28. Histological analysis revealed a significant reduction of cellular infiltration into the retina in EBI3(-/-) mice on day 16. Although Th1 cell responses and IRBP-specific IL-10 production were reduced in EBI3(-/-) mice, the development of Th17 cell responses was unaffected on day 9. On day 21, Th1 cell responses and IRBP-specific IL-10 production was restored to the same levels as that in EBI3(+/+) mice, and Th17 cell responses significantly increased in EBI3(-/-) mice. Furthermore, Foxp3 expression in CD4+ T cells was comparable between EBI3(+/+) and EBI3(-/-) mice on days 9 and 21. Therefore, these results indicate that EBI3 may be important in EAU initiation by Th1 cell responses and may suppress EAU by inhibition of both Th1 and Th17 cell responses in the late/maintenance phase.

First characterization of a teleost Epstein-Barr virus-induced gene 3 (EBI3) reveals a regulatory effect of EBI3 on the innate immune response of peripheral blood leukocytes

Epstein-Barr virus-induced gene 3 (EBI3) encodes a protein that in mammals is known to be a subunit of interleukin (IL)-27 and IL-35, both which regulate cytokine production and inflammatory response. To date, no studies on fish EBI3 have been documented. In this work, we report the identification of an EBI3 homologue, CsEBI3, from tongue sole (Cynoglossus semilaevis) and analysis of its expression and biological effect. CsEBI3 is composed of 245 amino acid residues and possesses a Fibronectin type 3 (FN3) domain that is preserved in lower and higher vertebrates. Expression of CsEBI3 was detected in a wide range of tissues, in particular those of immune relevant organs, and upregulated in a time-dependent manner by experimental challenge with bacterial and viral pathogens. Bacterial infection of peripheral blood leukocytes (PBL) enhanced CsEBI3 expression and caused extracellular secretion of CsEBI3. Purified recombinant CsEBI3 (rCsEBI3) stimulated the respiratory burst activity of PBL and upregulated the expression of IL-1β, IL-8, Myd88, interferon-induced gene 15, CD28, and chemokines. In contrast, rCsEBI3M, a mutant CsEBI3 that lacks the FN3 domain failed to activate PBL and induced much weaker expression of the immune genes. Treatment of PBL with rCsEBI3, but not with the mutant rCsEBI3M, enhanced cellular resistance against bacterial invasion, whereas antibody blocking of CsEBI3 on PBL significantly reduced cellular resistance against bacterial infection. Taken together, these results indicate for the first time that a teleost EBI3 possesses immunoregulatory property in a manner that is dependent on the conserved FN3 domain, and that CsEBI3 is involved in the innate immune defense of PBL against microbial pathogens.

Interleukin 35: a key mediator of suppression and the propagation of infectious tolerance

The importance of regulatory T cells (Tregs) in balancing the effector arm of the immune system is well documented, playing a central role in preventing autoimmunity, facilitating graft tolerance following organ transplantation, and having a detrimental impact on the development of anti-tumor immunity. These regulatory responses use a variety of mechanisms to mediate suppression, including soluble factors. While IL-10 and TGF-β are the most commonly studied immunosuppressive cytokines, the recently identified IL-35 has been shown to have potent suppressive function in vitro and in vivo. Furthermore, not only does IL-35 have the ability to directly suppress effector T cell responses, it is also able to expand regulatory responses by propagating infectious tolerance and generating a potent population of IL-35-expressing inducible Tregs. In this review, we summarize research characterizing the structure and function of IL-35, examine its role in disease, and discuss how it can contribute to the induction of a distinct population of inducible Tregs.

Lipopolysaccharide-induced M2 to M1 macrophage transformation for IL-12p70 production is blocked by Candida albicans mediated up-regulation of EBI3 expression

Macrophages are heterogeneous cell populations that are present in all tissues. Macrophages can be divided into classically activated inflammatory macrophages (M1) and alternatively activated anti-inflammatory macrophages (M2). It has been generally accepted that M1 macrophages are polarised in an inflammatory environment to produce pro-inflammatory cytokines, whilst M2 macrophages are involved in anti-inflammation and aid tissue repair in wound healing. Bacterial endotoxin (lipopolysaccharide; LPS) is a potent factor in infection, which induces M1 macrophages resulting in higher levels of iNOS, TNFα and IL-12p70 which dictate inflammatory T cell responses. M2 macrophages can be transformed into M1 macrophages following LPS stimulation to promote inflammation. Candida albicans is a commensal fungal microorganism, which has been suggested to induce immune tolerance; however, the mechanism of C. albicans-induced immune tolerance has not been investigated in detail. IL-35 is a recently identified anti-inflammatory cytokine which is a heterodimeric protein consisting of the Epstein-Barr virus-induced gene 3 (EBI3) and IL-12p35. IL-35 shares the protein subunit p35, with IL-12p70. IL-12p70 is the most potent cytokine to induce Th1 responses during inflammation. In this study, we demonstrate that heat-killed C. albicans (HKC) strongly suppressed LPS-induced IL-12p70 production in M2 macrophages. Candida albicans induced a high level of EBI3 expression in M2 macrophages, which served as a mechanism for IL-12p70 suppression by competitive binding of the common protein subunit (p35) of IL-35 and IL-12p70. To demonstrate that EBI3 expression had the ability to block IL-12p70 production intracellularly, a Chinese Hamster Ovary (CHO) cell line with biscistronic expression of IL-12p40 and p35 was constructed, followed by ectopic over-expression of EBI3. The over-expression of EBI3 in the IL-12p70 producing cell line effectively suppressed IL-12p70 production. IL-35 secretion was also detected in the cell line, with suppressed IL-12p70 production by immune-precipitation Western blotting. However, this secretion was not evident in M2 macrophages following stimulation by HKC. This can be explained by the constitutive expression of IL-35 receptors (gp130 and IL-12Rβ2) in M2 macrophages for cytokine consumption. Our results have indicated that C. albicans can suppress host inflammatory responses in mucosal skin by suppressing LPS-induced IL-12p70 production. Lower IL-12p70 production may avoid an unnecessary Th1 response in order to retain immune tolerance, which may be one of the mechanisms by which C. albicans achieves a successful commensal lifestyle without having a detrimental effect on the host’s health.

Interleukin-35: the future of hyperimmune-related diseases?

Interleukin (IL-35) is a newly identified heterodimeric cytokine belonging to the IL-12 family. It contains Epstein-Barr virus-induced gene 3 subunit and IL-27 p35 subunit. Although its receptor and signaling pathway are not clear, we presumed that its receptor is composed by two chains that might be similar to those receptors of IL-12, IL-23, and IL-27. We also believe that the signal transducer activator of transcription family members is involved in its signaling pathway. It was reported that IL-35 could suppress Teff cell proliferation and Th17 development. It was considered to have a potential therapeutic effect against immune diseases. In our perspective, the finding of IL-35 is of great significance, since it can regulate T cells, which is an important therapeutic target of immunological disorders. IL-35 would promote the development of different kinds of vaccines, even vaccine for special cancer, and be promising to cure autoimmune and inflammatory diseases.

Epstein-Barr virus-induced gene 3 negatively regulates neuroinflammation and T cell activation following coronavirus-induced encephalomyelitis

Epstein-Barr virus-induced gene 3 (EBI3) associates with p28 and p35 to form the immunomodulatory cytokines IL-27 and IL-35, respectively. Infection of EBI3-/- mice with the neuroadapted JHM strain of mouse hepatitis virus (JHMV) resulted in increased mortality that was not associated with impaired ability to control viral replication but enhanced T cell and macrophage infiltration into the CNS. IFN-γ secretion from virus-specific CD4+ and CD8+ T cells isolated from infected EBI3-/- mice was augmented while IL-10 expression muted in comparison to infected WT mice. These data demonstrate a regulatory role for EBI3-associated cytokines in controlling host responses following CNS viral infection.

Interleukin-27 priming of T cells controls IL-17 production in trans via induction of the ligand PD-L1

Interleukin-27 (IL-27) is a key immunosuppressive cytokine that counters T helper 17 (Th17) cell-mediated pathology. To identify mechanisms by which IL-27 might exert its immunosuppressive effect, we analyzed genes in T cells rapidly induced by IL-27. We found that IL-27 priming of naive T cells upregulated expression of programmed death ligand 1 (PD-L1) in a signal transducer and activator of transcription 1 (STAT1)-dependent manner. When cocultured with naive CD4(+) T cells, IL-27-primed T cells inhibited the differentiation of Th17 cells in trans through a PD-1-PD-L1 interaction. In vivo, coadministration of naive TCR transgenic T cells (2D2 T cells) with IL-27-primed T cells expressing PD-L1 inhibited the development of Th17 cells and protected from severe autoimmune encephalomyelitis. Thus, these data identify a suppressive activity of IL-27, by which CD4(+) T cells can restrict differentiation of Th17 cells in trans.

A computational profiling of changes in gene expression and transcription factors induced by vFLIP K13 in primary effusion lymphoma

Infection with Kaposi's sarcoma associated herpesvirus (KSHV) has been linked to the development of primary effusion lymphoma (PEL), a rare lymphoproliferative disorder that is characterized by loss of expression of most B cell markers and effusions in the body cavities. This unique clinical presentation of PEL has been attributed to their distinctive plasmablastic gene expression profile that shows overexpression of genes involved in inflammation, adhesion and invasion. KSHV-encoded latent protein vFLIP K13 has been previously shown to promote the survival and proliferation of PEL cells. In this study, we employed gene array analysis to characterize the effect of K13 on global gene expression in PEL-derived BCBL1 cells, which express negligible K13 endogenously. We demonstrate that K13 upregulates the expression of a number of NF-κB responsive genes involved in cytokine signaling, cell death, adhesion, inflammation and immune response, including two NF-κB subunits involved in the alternate NF-κB pathway, RELB and NFKB2. In contrast, CD19, a B cell marker, was one of the genes downregulated by K13. A comparison with K13-induced genes in human vascular endothelial cells revealed that although there was a considerable overlap among the genes induced by K13 in the two cell types, chemokines genes were preferentially induced in HUVEC with few exceptions, such as RANTES/CCL5, which was induced in both cell types. Functional studies confirmed that K13 activated the RANTES/CCL5 promoter through the NF-κB pathway. Taken collectively, our results suggest that K13 may contribute to the unique gene expression profile, immunophenotype and clinical presentation that are characteristics of KSHV-associated PEL.

Regulation of proinflammatory Th17 responses during Trypanosoma cruzi infection by IL-12 family cytokines

Previously, we reported that the transcription factor T-bet (Tbx21) regulates Th17 responses to Trypanosoma cruzi infection in an IFN-γ-independent manner. In an effort to further understand this regulation, we examined the development and plasticity of Th17 cells during T. cruzi infection. Th17 cells recovered from infected Tbx21(-/-) mice were amenable to the inhibitory effects of T-bet, as ectopic expression of T-bet reduced IL-17 expression. We subsequently addressed the role of IL-12 family cytokines IL-12 and IL-27 and report that IL-12p35(-/-) mice infected with T. cruzi exhibited a significant increase in Th17 cells and Th17-associated inflammation. Ex vivo culture of these cells with IL-12 led to a dramatic reduction in IL-17 production and concomitant increase in IFN-γ. Importantly, the ability of IL-12 to suppress IL-17 was independent of IFN-γ. Surprisingly, and contrary to results reported for other pathogens, IL-27 had no inhibitory effect on Th17 development, as Ebi-3(-/-) mice failed to show any increase in their T. cruzi-specific Th17 response. Furthermore, IL-27 could not compensate or synergize with IL-12 to suppress IL-17 production ex vivo. Thus, we have established that IL-12, not IL-27, is critical for regulating Th17 responses to T. cruzi.

New directions in the basic and translational biology of interleukin-27

Interleukin (IL)-27 is a member of the IL-6 and IL-12 family composed of the IL-27p28 and Epstein-Barr virus-induced gene 3 (EBI3) subunits. Although IL-27 was originally identified as a proinflammatory factor, subsequent studies have revealed the pleiotropic nature of this cytokine. This review discusses recent work that has explored the effect of IL-27 on CD4(+) T cell subsets, including T regulatory type 1 (Tr-1) cells, T follicular helper cells (Tfhs), and forkhead box P3 (Foxp3)(+) T regulatory cells (Tregs). Additionally, we highlight studies that have identified a role for the IL-27p28 subunit as a cytokine receptor antagonist. Much of the recent work on IL-27 has been relevant to human disease states characterized by inappropriate or excessive inflammation, and this review discusses potential opportunities to use IL-27 as a therapeutic agent.