Activity Of IL-27 Research Articles

IL-27 disturbs lipid metabolism and restrains mitochondrial activity to inhibit γδ T17 cell-mediated skin inflammation

IL-17+ γδ T cells (γδ T17) are kick-starters of inflammation due to their strict immunosurveillance of xenobiotics or cellular damages and rapid response to pro-inflammatory stimulators. IL-27 is a well-recognized pleiotropic immune regulator with potent inhibitory effects on type 17 immune responses. However, its actions on γδ T17 mediated inflammation and the underlying mechanisms are less well understood. Here we find that IL-27 inhibits the production of IL-17 from γδ T cells. Mechanistically, IL-27 promotes lipolysis while inhibits lipogenesis, thus reduces the accumulation of lipids and subsequent membrane phospholipids, which leads to mitochondrial deactivation and ensuing reduction of IL-17. More importantly, Il27ra deficient γδ T cells are more pathogenic in an imiquimod-induced murine psoriasis model, while intracutaneous injection of rmIL-27 ameliorates psoriatic inflammation. In summary, this work uncovered the metabolic basis for the immune regulatory activity of IL-27 in restraining γδ T17 mediated inflammation, which provides novel insights into IL-27/IL-27Ra signaling, γδ T17 biology and the pathogenesis of psoriasis.

B cell-intrinsic IL-27 and IFNγ receptor signaling drive PD-L1 expression, IgG2a autoantibody production, VEGF-dependent tumor angiogenesis and cancer progression

Abstract B effector cells produce Abs and autoantibodies, while B regulatory cells use cytokines and transmembrane proteins to fine tune immune functions. Our lab recently revealed that tumor-infiltrating B cells produce IL-27 to promote immune evasion, partly by upregulating tumoral PD-L1, including that expressed by B cells per se. To investigate the autocrine activity of IL-27 in tumor progression, we generated μMT:Il27ra–/– bone marrow chimera mice lacking the IL-27 receptor specifically in B cells. These mice displayed substantially reduced tumor growth from orthotopically engrafted ER+ E0771 breast cancer cells, as associated with only moderately decreased PD-L1 levels but, unexpectedly, severely compromised blood vessel integrity. The residual PD-L1 levels and tumor growth were virtually abolished by additional B cell-specific deficiency in IFNγ receptor signaling, as occurring in double KO μMT:Il27ra–/–Ifngr1–/– mice, in which the microvessel permeability was also worsened. Mechanistically, this aligned with our findings that IL-27-producing B cells expressed high levels of VEGFA, whose transcription in activated B cells could be further enhanced by IL-27 and IFNγ. Double KO mice also lacked anti-dsDNA IgG2a autoantibodies, as elicited by tumor engraftment. Thus, B cell-intrinsic IL-27 and IFNγ receptor signaling synergize to promote B-cell PD-L1 expression, IgG2a autoantibody production, and vascular integrity, all of which may contribute to cancer development.

E069 Antagonism of IL-27 bioactivity

Abstract Background/Aims Rheumatoid arthritis (RA) is a chronic autoimmune disease that results in joint damage and bony destruction. The inflammatory process is central in the pathology of RA, with cytokines mediating the inflammatory response. Cytokines, in particular IL-6, have been targeted as treatments for RA. The IL-27 cytokine is part of the IL-6 family, and acts via the same signalling pathway. IL-27 can have the same function as IL-6, but can also antagonise IL-6. The presence of ectopic lymphoid structures (ELSs) is associated with more severe disease and worse joint damage, and is also associated with low IL-27 levels. Hence, targeting IL-27 may aid in severe RA and offer a novel treatment option. Aims: 1) To generate a recombinant IL-27 antagonist, 2) to determine the concentration and bioactivity of IL-27 antagonist, 3) to test the bioactivity of IL-27 antagonist as an inhibitor of IL-27 activity. Methods Chinese hamster ovarian (CHO) cells were transduced with adenovirus to express the IL-27 antagonist. The concentration of these IL-27 antagonists was determined using ELISA. To determine the bioactivity of the IL-27 antagonist, both acute leukaemia cell lines (THP1 cells) and cells from C57BL/6J mice were treated with human IL-27 and IL-27 antagonists and STAT3 activation determined using flow cytometry and ELISA. Results THP1 cells treated with both 5ng/ml and 15ng/ml of human recombinant IL-27 showed STAT3 activation, with 29.4% and 30.7% of cells being STAT3 positive respectively. Cells that remained untreated only showed STAT3 activation in 2.54% of cells, indicating IL-27 has a role in the activation of the STAT3 pathway. STAT3 activation was not witnessed in CD4 cells from C57BL/6J mice treated with human recombinant IL-27. Furthermore, the recombinant IL-27 antagonist was not seen to be able to antagonise the actions IL-27 and alter STAT3 activation. Conclusion In conclusion, this study has demonstrated that IL-27 treatment of cells can cause increased STAT3 activation, however we were unable to demonstrate that the IL-27 antagonist was able to inhibit the actions of IL-27. IL-27 shows great potential for use as a novel therapy, since both its pro and anti-inflammatory functions can be targeted, however there needs to be much more information about the action of IL-27 as this is still largely unknown. Future studies could aim to optimise the protocol in order to understand the bioactivity of the IL-27 antagonist, thus understanding its role in altering STAT3 activation. Disclosure L. Green: None.

Glycosaminoglycans bind human IL-27 and regulate its activity.

IL-27 is a cytokine of the IL-12 family, composed of EBI3 and IL-27p28. IL-27 regulates immune responses and also other physiological processes including hematopoiesis, angiogenesis, and bone formation. Its receptor, composed of IL-27Rα and gp130, activates the STAT pathway. Here, we show that different glycosaminoglycans (GAGs) modulate human IL-27 activity in vitro. We find that soluble heparin and heparan sulfate efficiently inhibit human IL-27 activity as shown by decreased STAT signaling and downstream biological effects. In contrast, membrane-bound heparan sulfate seems to positively regulate IL-27 activity. Our biochemical studies demonstrate that soluble GAGs directly bind to human IL-27, consistent with in silico analyses, and prevent its binding to IL-27Rα. Although murine IL-27 also bound to GAGs in vitro, its activity was less efficiently inhibited by soluble GAGs. Lastly, we show that two heparin-derivatives, low molecular weight heparin and fondaparinux, that like unfractionated heparin are used in clinics, had weaker or no effect on human IL-27 activity. Together, our data identify GAGs as new players in the regulation of human IL-27 activity that might act under physiological conditions and may also have a clinical impact in heparin-treated patients.

Effect of Novel Molecules Against Inflammation in Lipopolysaccharide (LPS)‐Stimulated Fibroblast‐Like Synoviocytes (FLS)

Arthritis refers to a joint disorder which features inflammation of one or more joints within the body, often resulting in pain, stiffness, swelling and decreased range of motion of joints. There are two main forms of arthritis—osteoarthritis (OA) and rheumatoid arthritis (RA)—and they both cause damage to the joints in different ways. OA, the most common form of arthritis, entails the wearing away of the cartilage that protects the bones in joint spaces and RA involves the immune system attacking the synovial lining of the joints. The disease process of all forms of arthritis can cause permanent joint damage and there are limited treatments to reverse its physical changes, making it essential to gain an understanding of the general pathology of arthritis. The pathogenesis of arthritis is complex, and includes many cell types, but an inflammatory reaction is a common characteristic and has been studied extensively with various forms of arthritis. A specialized cell type, fibroblast‐like synoviocytes (FLS) in the synovial intimal lining of the joint, have been shown to play a crucial role in the pathogenesis of chronic inflammatory diseases, such as arthritis, as they produce pro‐inflammatory cytokines and cartilage‐degrading mediators. In our recent research, the inflammation activity of FLS have been characterized in vitro via the stimulation of lipopolysaccharide (LPS) for a fixed quantity of time, in this case 6 hours, and then analyzing the effect of LPS on the expression of genes representing acute inflammation in FLS, such as interleukin (IL)‐1β, IL‐6, tumor necrosis factor α (TNF‐α), and matrix metalloproteinases (MMPs). It has been shown that the gene expression of IL‐6 is an ideal marker of pro‐inflammatory activity of FLS. Beyond understanding the pro‐inflammatory responses of FLS, novel compounds have been utilized in our laboratory to counteract the stimuli of LPS, which results in FLS expressing an anti‐inflammatory response. One configuration of the novel compounds were synthesized to mimic the interaction region between Pigment Epithelium Derived Factor (PEDF) and its receptor Laminin Receptor 1 (LAMR1) and the other consists of the activity of IL‐27, which both have promising anti‐inflammatory effects on FLS at low dosages. The overall aim of this study is to investigate the effect of the novel molecules against inflammation in lipopolysaccharide (LPS)–stimulated fibroblast‐like synoviocytes (FLS) by analyzing the expression of various pro‐inflammatory cytokines and cartilage degrading mediators. In future directions of the study, second generation molecules are to be developed to enhance drug affinity and to lower the effective dosage amount, making the molecules better‐suited for clinical translation, which would be later used as a therapeutic method that would control the inflammation activity of FLS and repair the cartilage in the joint undergoing a form of arthritis.Support or Funding InformationWe acknowledge support from NIH‐1R01AR069079 (MLF).

Impact of IL-27 on hepatocyte antiviral gene expression and function

Background: Interleukin (IL)-27 is a member of the IL-6/IL-12 family of cytokines. It is a potent cytokine, with potential antiviral impact, and has been shown to play a role in modulating functions of diverse cell types, including Th1, Th2, and NK and B cells, demonstrating both pro- and anti-inflammatory roles. In hepatocytes, it is capable of inducing signal transducer and activator of transcription (STAT)1, STAT3 and interferon-stimulated genes. Methods: To address its role in viral hepatitis, the antiviral activity of IL-27 against hepatitis C virus (HCV) and hepatitis B virus (HBV) was tested in vitro using cell-culture-derived infectious HCV (HCVcc) cell culture system and the HepaRG HBV cell culture model. To further investigate the impact of IL-27 on hepatocytes, Huh7.5 cells were treated with IL-27 to analyse the differentially expressed genes by microarray analysis. Furthermore, by quantitative PCR, we analyzed the up-regulation of chemokine (CXCL)-10 in response to IL-27. Results: In both HCV and HBV infection models, we observed only a modest direct antiviral effect. Microarray analysis showed that the up-regulated genes mostly belonged to antigen presentation and DNA replication pathways, and involved strong up-regulation of CXCL-10, a gene associated with liver inflammation. Overall, gene set enrichment analysis showed a striking correlation of these genes with those up-regulated in response to related cytokines in diverse cell populations. Conclusion: Our data indicate that IL-27 can have a significant pro-inflammatory impact in vitro, although the direct antiviral effect is modest. It may have a potential impact on hepatocyte function, especially chemokine expression and antigen presentation.

Impact of IL-27 on hepatocyte antiviral gene expression and function.

Background: Interleukin (IL)-27 is a member of the IL-6/IL-12 family of cytokines. It is a potent cytokine, with potential antiviral impact, and has been shown to play a role in modulating functions of diverse cell types, including Th1, Th2, and NK and B cells, demonstrating both pro- and anti-inflammatory roles. In hepatocytes, it is capable of inducing signal transducer and activator of transcription (STAT)1, STAT3 and interferon-stimulated genes. Methods: To address its role in viral hepatitis, the antiviral activity of IL-27 against hepatitis C virus (HCV) and hepatitis B virus (HBV) was tested in vitro using cell-culture-derived infectious HCV (HCVcc) cell culture system and the HepaRG HBV cell culture model. To further investigate the impact of IL-27 on hepatocytes, Huh7.5 cells were treated with IL-27 to analyse the differentially expressed genes by microarray analysis. Furthermore, by quantitative PCR, we analyzed the up-regulation of chemokine (CXCL)-10 in response to IL-27. Results: In both HCV and HBV infection models, we observed only a modest direct antiviral effect. Microarray analysis showed that the up-regulated genes mostly belonged to antigen presentation and DNA replication pathways, and involved strong up-regulation of CXCL-10, a gene associated with liver inflammation. Overall, gene set enrichment analysis showed a striking correlation of these genes with those up-regulated in response to related cytokines in diverse cell populations. Conclusion: Our data indicate that IL-27 can have a significant pro-inflammatory impact in vitro, although the direct antiviral effect is modest. It may have a potential impact on hepatocyte function, especially chemokine expression and antigen presentation.

Proteomic analysis uncovers common effects of IFN-γ and IL-27 on the HLA class I antigen presentation machinery in human cancer cells.

IL-27, a member of the IL-12-family of cytokines, has shown anti-tumor activity in several pre-clinical models due to anti-proliferative, anti-angiogenic and immune-enhancing effects. On the other hand, IL-27 demonstrated immune regulatory activities and inhibition of auto-immunity in mouse models. Also, we reported that IL-27, similar to IFN-γ, induces the expression of IL-18BP, IDO and PD-L1 immune regulatory molecules in human cancer cells. Here, a proteomic analysis reveals that IL-27 and IFN-γ display a broad overlap of functions on human ovarian cancer cells. Indeed, among 990 proteins modulated by either cytokine treatment in SKOV3 cells, 814 showed a concordant modulation by both cytokines, while a smaller number (176) were differentially modulated. The most up-regulated proteins were common to both IFN-γ and IL-27. In addition, functional analysis of IL-27-regulated protein networks highlighted pathways of interferon signaling and regulation, antigen presentation, protection from natural killer cell-mediated cytotoxicity, regulation of protein polyubiquitination and proteasome, aminoacid catabolism and regulation of viral protein levels.Importantly, we found that IL-27 induced HLA class I molecule expression in human cancer cells of different histotypes, including tumor cells showing very low expression. IL-27 failed only in a cancer cell line bearing a homozygous deletion in the B2M gene. Altogether, these data point out to a broad set of activities shared by IL-27 and IFN-γ, which are dependent on the common activation of the STAT1 pathway. These data add further explanation to the anti-tumor activity of IL-27 and also to its dual role in immune regulation.

Immune Regulation of Interleukin-27 in Malignant Pleural Effusion.

Background:Interleukin (IL)-27 has been reported to have anti-proliferate and anti-angiogenic activities on cancer cells. However, the involvement of IL-27 in malignant pleural effusion (MPE) remains unknown. Thus, in this research, we compared the immune functions of IL-27, interferon (IFN)-γ, and IL-17 on lung cancer cells and revealed the regulatory mechanism of IL-27 in MPE.Methods:The distribution of IL-27 in both MPE and blood was evaluated by enzyme-linked immunosorbent assay and flow cytometry. The expressions of cytokine receptors and the levels of the phosphorylated signal transducer and activator of transcription (STAT) signalings were detected by flow cytometry. As well as the effects of proliferation, apoptosis, migration, and adherent activity of IL-27, IFN-γ, and IL-17 on lung cancer cells were also explored.Results:The expression of IL-27 was increased in MPE when compared with blood (147.3 ± 25.1 pg/ml vs. 100.3 ± 13.9 pg/ml, P = 0.04). IL-27 was noted to suppress both proliferation (18.33 ± 0.21 vs. 27.77 ± 0.88, P = 0.0005) and migration (1.82 ± 0.44 vs. 3.13 ± 0.07, P = 0.04) of A549 cells, but obviously promoted apoptosis of A549 cells (9.47 ± 1.14 vs. 4.96 ± 0.17, P = 0.02) by activating STAT1 signaling. Interestingly, IL-27 played totally opposite effects on A549 cells by activating STAT3 pathway. Moreover, IL-27 exerted different intercellular adherent activities of A549 cells to pleural mesothelial cell monolayer by activating different STAT signalings.Conclusions:IL-27 might exert an important immune regulation on lung cancer cells in human pleural malignant environment.

IL-27 in Human Secondary Lymphoid Organs Attracts Myeloid Dendritic Cells and Impairs HLA Class I–Restricted Antigen Presentation

Different cytokines play crucial roles in inflammation and in polarizing immune responses, including IL-27 that exerts pro- and anti-inflammatory functions. Although the activity of IL-27 is well characterized in murine immune cells, only limited information is available regarding the natural cellular sources of IL-27 in humans and its effects on human immune cells. Dendritic cells (DCs) are the most potent professional APCs that in the immature state are positioned throughout peripheral tissues by acting as sentinels, sensing the presence of Ags. Activated DCs migrate into the lymph nodes and direct Ag-specific T cell responses, thus acting as key players in both adaptive and innate immunity. In this study we asked whether IL-27 is produced by human secondary lymphoid organs and what is its functional role on human DCs. To our knowledge, we provide the first evidence that 1) in lymph nodes, macrophages are the major source for IL-27; 2) immature and mature human DCs express functional IL-27R; 3) IL-27 exerts immunosuppressive activity by crippling the Ag processing machinery in immature DCs under steady-state conditions and after pulsing with a viral Ag; and 4) IL-27 is chemotactic for human DCs. Our findings highlight novel mechanisms underlying the immunosuppressive activity of IL-27, suggesting that this cytokine may function as a homeostatic cytokine in secondary lymphoid organs by limiting duration and/or intensity of ongoing adaptive immune responses. The results presented in this study pave the way to future studies aimed at investigating whether dysregulation of IL-27 expression and function may be involved in pathogenesis of autoimmune disease and cancer.

Activation of IL‐27 signalling promotes development of postinfluenza pneumococcal pneumonia

Postinfluenza pneumococcal pneumonia is a common cause of death in humans. However, the role of IL-27 in the pathogenesis of secondary pneumococcal pneumonia after influenza is unknown. We now report that influenza infection induced pulmonary IL-27 production in a type I IFN-α/β receptor (IFNAR) signalling-dependent manner, which sensitized mice to secondary pneumococcal infection downstream of IFNAR pathway. Mice deficient in IL-27 receptor were resistant to secondary pneumococcal infection and generated more IL-17A-producing γδ T cells but not αβ T cells, thereby leading to enhanced neutrophil response during the early phase of host defence. IL-27 treatment could suppress the development of IL-17A-producing γδ T cells activated by Streptococcus pneumoniae and dendritic cells. This suppressive activity of IL-27 on γδ T cells was dependent on transcription factor STAT1. Finally, neutralization of IL-27 or administration of IL-17A restored the role of γδ T cells in combating secondary pneumococcal infection. Our study defines what we believe to be a novel role of IL-27 in impairing host innate immunity against pneumococcal infection.

Interferon-γ, tumor necrosis factor, and interleukin-18 cooperate to control growth of Mycobacterium tuberculosis in human macrophages

Mycobacterium tuberculosis (MTB) remains a leading infectious threat to human health. Macrophages are the cells targeted for infection by the bacterium as well as key effector cells for clearance of the pathogen. Interleukin (IL)-27 opposes macrophage-mediated control of MTB because supplying IL-12 and blocking the activity of IL-27 limits bacterial growth in primary human macrophages. The purpose of this study was to determine the immunological regulators of this macrophage mechanism to restrict MTB growth. Interferon (IFN)-γ, TNF-α, and IL-18 were all demonstrated to be important to the environment that limits bacterial growth when IL-12 is supplied and IL-27 is neutralized. We find IL-18 works in conjunction with IL-12 to achieve optimal IFN-γ production in this system. We also demonstrate novel interactions between these cytokines to influence the expression or responsiveness to one another. Quantitative assays show that IFN-γ enhances expression of the IL-18 receptor signaling chain, as well as TNF expression and secretion. In turn, TNF-α augments expression of the receptor for IFN-γ, the amount at the cell surface, and the extent of IFN-γ -induced signaling. We further define how the cytokine environment supports an enhanced state of classical macrophage activation. Collectively, these results describe novel immunological mechanisms that provide additional insights into the effects of IL-12 and IL-27 on macrophage regulation during MTB infection.

IL-27 Regulates IL-18 Binding Protein in Skin Resident Cells

IL-18 is an important mediator involved in chronic inflammatory conditions such as cutaneous lupus erythematosus, psoriasis and chronic eczema. An imbalance between IL-18 and its endogenous antagonist IL-18 binding protein (BP) may account for increased IL-18 activity. IL-27 is a cytokine with dual function displaying pro- and anti-inflammatory properties. Here we provide evidence for a yet not described anti-inflammatory mode of action on skin resident cells. Human keratinocytes and surprisingly also fibroblasts (which do not produce any IL-18) show a robust, dose-dependent and highly inducible mRNA expression and secretion of IL-18BP upon IL-27 stimulation. Other IL-12 family members failed to induce IL-18BP. The production of IL-18BP peaked between 48–72 h after stimulation and was sustained for up to 96 h. Investigation of the signalling pathway showed that IL-27 activates STAT1 in human keratinocytes and that a proximal GAS site at the IL-18BP promoter is of importance for the functional activity of IL-27. The data are in support of a significant anti-inflammatory effect of IL-27 on skin resident cells. An important novel property of IL-27 in skin pathobiology may be to counter-regulate IL-18 activities by acting on keratinocytes and importantly also on dermal fibroblasts.

Human TCRγδ+T cells represent a novel target for IL‐27 activity

IL-27 and TCRγδ(+) T lymphocytes play critical roles in both innate and adaptive immune responses in health and disease, including infection and tumors. Although the activity of IL-27 is well characterized in different human immune cells, no information is available on the role of IL-27 in human TCRγδ(+) T lymphocytes. Here, we provide the first evidence that TCRγδ(+) T lymphocytes express both gp130 and WSX-1 chains of IL-27R, and that IL-27 may function in TCRγδ(+) T cells by (i) inducing STAT1 and STAT3 phosphorylation, (ii) stimulating cytotoxicity against tumor cells through upregulation of cytotoxic granules production, (iii) reducing the release of Th2-related cytokines, such as IL-5 and IL-13, and inducing IFN-γ production, and (iv) upregulating the expression of CD62L. These results highlighted a novel immunoregulatory property of human IL-27 that may be relevant in the immune response against tumors. Our results may offer new perspectives for the development of future clinical trials using IL-27 and TCRγδ(+) cells for cancer immunotherapy.

IL-27 priming of T cells controls IL-17-production in trans via induction of PD-L1 (59.1)

Abstract Interleukin (IL)-27 is a key immunosuppressive cytokine that counters Th17-mediated pathology. To identify mechanisms by which IL-27 might exert its immunosuppressive effect, we analyzed genes in naïve CD4+ T cells rapidly induced by IL-27 stimulation for 3 hours. We discovered that IL-27 priming of naïve T cells upregulated expression of the ligand of PD-1 (PD-L1) in a STAT1-dependent manner. To assess the relevance of IL-27 in controlling PD-L1 expression in vivo, we employed a T. gondii infection model in which IL-27 is important for controlling immunopathology. We found that expression of PD-L1 on CD4+ T cells was significantly lower in EBI3-/- mice. When added to naïve CD4+ T cells, IL-27-primed T cells inhibited the differentiation of Th17 cells in trans in vitro. In vivo, co-administration of IL-27-primed T cells expressing PD-L1 inhibited the development of Th17 cells and protected from severe autoimmune encephalomyelitis. Moreover this inhibitory effect of IL-27 in vivo was largely reversed by elimination of PD-L1 on T cells. Thus, these data identify a novel suppressive activity of IL-27, by which CD4+ T cells can restrict differentiation of Th17 cells in trans. It is conceivable that the strategy of IL-27-pretreatment of naïve T cells ex vivo with subsequent adoptive transfer might be used therapeutically to attenuate autoimmune disease.

Antiangiogenic and Antitumor Activities of IL-27

IL-27 is a novel IL-6/IL-12 family cytokine playing an important role in the early regulation of Th1 responses. We have recently demonstrated that IL-27 has potent antitumor activity, which is mainly mediated through CD8(+) T cells, against highly immunogenic murine colon carcinoma. In this study, we further evaluated the antitumor and antiangiogenic activities of IL-27, using poorly immunogenic murine melanoma B16F10 tumors, which were engineered to overexpress single-chain IL-27 (B16F10 + IL-27). B16F10 + IL-27 cells exerted antitumor activity against not only s.c. tumor but also experimental pulmonary metastasis. Similar antitumor and antimetastatic activities of IL-27 were also observed in IFN-gamma knockout mice. In NOD-SCID mice, these activities were decreased, but were still fairly well-retained, suggesting that different mechanisms other than the immune response are also involved in the exertion of these activities. Immunohistochemical analyses with Abs against vascular endothelial growth factor and CD31 revealed that B16F10 + IL-27 cells markedly suppressed tumor-induced neovascularization in lung metastases. Moreover, B16F10 + IL-27 cells clearly inhibited angiogenesis by dorsal air sac method, and IL-27 exhibited dose-dependent inhibition of angiogenesis on chick embryo chorioallantoic membrane. IL-27 was revealed to directly act on HUVECs and induce production of the antiangiogenic chemokines, IFN-gamma-inducible protein (IP-10) and monokine induced by IFN-gamma. Finally, augmented mRNA expression of IP-10 and monokine induced by IFN-gamma was detected at the s.c. B16F10 + IL-27 tumor site, and antitumor activity of IL-27 was partially inhibited by the administration of anti-IP-10. These results suggest that IL-27 possesses potent antiangiogenic activity, which plays an important role in its antitumor and antimetastatic activities.

Characterization of the IL-12 family of cytokines in human dendritic cells infected with live Chlamydia trachomatis

Chlamydia trachomatis (CT) is a clinically important pathogen. In 2–5% of cases, infection results in the development of reactive arthritis. We have previously shown that human dendritic cells (DC) can be readily infected with live CT following in vitro exposure [1]. Infected DC efficiently process chlamydia and present chlamydial antigens to both CD4+ [1] and CD8+ T cells [1,2]. Infected DC also produce a number of cytokines including IL-12 and tumour necrosis factor alpha but not IL-10 [1]. The production of IL-12 following infection gives DC the ability to stimulate Th1 responses to chlamydia. Here we have investigated production of another two cytokines from the IL-12 family – IL-23 and IL-27 – by DC infected with live CT. The results were compared with those obtained following DC activation with other inflammatory stimuli. IL-23 is a heterodimer composed of p19 and p40 subunits, where the p40 subunit is shared between IL-23 and IL-12. IL-27 is a heterodimer composed of p28 and Epstein–Barr virus-induced protein 3 (EBI3) subunits. The main function of both of these cytokines is to stimulate interferon gamma (IFN-γ) production in T cells. However, whereas IL-27 activity primarily affects naive T cells, IL-23 stimulates both primed and memory cells.

Potent antitumor activity of interleukin-27.

Although much promising data that interleukin (IL)-12 could be a powerful therapeutic agent against cancer were reported in animal models, its excessive toxicity has become a problem for its clinical application. IL-27 is a novel IL-12 family member that plays a role in the early regulation of T helper cell 1 initiation, including induction of T-bet and IL-12 receptor beta 2 expression. In the present study, we have evaluated the antitumor activity of IL-27 against a murine tumor model of colon carcinoma C26. C26 cells, which were transduced with the single-chain IL-27 cDNA and became secreting IL-27 (C26-IL-27), exhibited minimal tumor growth in vivo, and all of the mice inoculated with these cells survived healthily with complete tumor remission. Inoculation of mice with C26-IL-27 induced enhanced IFN-gamma production and cytotoxic T-lymphocyte activity against C26 tumor in spleen cells. Recovered mice from the inoculation showed a tumor-specific protective immunity to the following challenge with parental C26 tumor. The antitumor activity of IL-27 was almost diminished in nude mice, and depletion of CD8(+) T cells and neutralization of IFN-gamma in immunocompetent mice reduced greatly the antitumor activity. Moreover, the antitumor activity was abolished in T-bet-deficient mice, whereas it was observed unexpectedly in mice deficient of signal transducer and activator of transcription (STAT) 4. These results suggest that IL-27 has potent abilities to induce tumor-specific antitumor activity and protective immunity and that the antitumor activity is mediated mainly through CD8(+) T cells, IFN-gamma, and T-bet but not through STAT4.