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The interleukin IL27 promotes expansion and differentiation of hematopoietic stem cells into myeloid progenitor cells. Many tumor-infiltrating myeloid cells exert immunosuppressive effects, but we hypothesized that the myeloid cells induced by IL27 would have antitumor activity. In this study, we corroborated this hypothesis as investigated in two distinct mouse transplantable tumor models. Malignant mouse cells engineered to express IL27 exhibited reduced tumor growth in vivo. Correlated with this effect was a significant increase in the number of tumor-infiltrating CD11b+ myeloid cells exhibiting a reduced immunosuppressive activity. Notably, these CD11b+ cells were characterized by an activated M1 macrophage phenotype, on the basis of increased expression of inducible nitric oxide synthase and other M1 biomarkers. In vivo depletion of these cells by administering anti–Gr-1 eradicated the antitumor effects of IL27. When admixed with parental tumors, CD11b+ cells inhibited tumor growth and directly killed the tumor in a nitric oxide-dependent manner. Mechanistically, IL27 expanded Lineage−Sca-1+c-Kit+ cells in bone marrow. Transplant experiments in Ly5.1/5.2 congenic mice revealed that IL27 directly acted on these cells and promoted their differentiation into M1 macrophages, which mobilized into tumors. Overall, our results illustrated how IL27 exerts antitumor activity by enhancing the generation of myeloid progenitor cells that can differentiate into antitumorigenic M1 macrophages.Significance: These findings show how the interleukin IL27 exerts potent antitumor activity by enhancing the generation of myeloid progenitor cells that can differentiate into antitumorigenic M1 macrophages.Cancer Res; 78(1); 182–94. ©2017 AACR.

This file contains Supplemental Table 1, Supplementary Figure Legends, and Supplementary Figures. Supplemental Table 1 shows primers used in this study. Supplementary Figure Legends describe the legend for each supplementary figure. Figure S1 shows the gating strategy in flow cytometry analysis. Figure S2 shows that IL-27 augments the infiltration of CD11b+ myeloid cells into MC38 tumor. Figure S3 shows that IL-27 promotes the differentiation into M1 macrophages in MC38 tumor-bearing mice. Figure S4 shows that IL-27 much less but significantly augments the infiltration of M1 macrophages into B16F10 tumor when the tumor size in B16F10-IL-27 tumor-bearing mice reaches the similar tumor size to that in control tumor-bearing mice. Figure S5 shows that IL-27 inhibits the differentiation into immunosuppressive macrophages in MC38 tumor-bearing mice. Figure S6 shows the therapeutic potential of the CD11b+ myeloid cells purified from tumors of B16F10-IL-27 tumor-bearing mice on pre-existing tumor model. Figure S7 shows that IL-27-induced MC38 tumor-infiltrating myeloid cells exert direct antitumor effects by killing tumor through NO. Figure S8 shows that the enhanced mRNA expression of immune checkpoint molecules and TGF-β1 in CD11b+ myeloid cells in IL-27-expressing tumor-bearing mice.

Hematopoiesis is hierarchically orchestrated by a very small population of hematopoietic stem cells (HSCs) that reside in the bone-marrow niche and are tightly regulated to maintain homeostatic blood production. HSCs are predominantly quiescent, but they enter the cell cycle in response to inflammatory signals evoked by severe systemic infection or injury. Thus, hematopoietic stem and progenitor cells (HSPCs) can be activated by pathogen recognition receptors and proinflammatory cytokines to induce emergency myelopoiesis during infection. This emergency myelopoiesis counterbalances the loss of cells and generates lineage-restricted hematopoietic progenitors, eventually replenishing mature myeloid cells to control the infection. Controlled generation of such signals effectively augments host defense, but dysregulated stimulation by these signals is harmful to HSPCs. Such hematopoietic failure often results in blood disorders including chronic inflammatory diseases and hematological malignancies. Recently, we found that interleukin (IL)-27, one of the IL-6/IL-12 family cytokines, has a unique ability to directly act on HSCs and promote their expansion and differentiation into myeloid progenitors. This process resulted in enhanced production of neutrophils by emergency myelopoiesis during the blood-stage mouse malaria infection. In this review, we summarize recent advances in the regulation of myelopoiesis by proinflammatory cytokines including type I and II interferons, IL-6, IL-27, granulocyte colony-stimulating factor, macrophage colony-stimulating factor, and IL-1 in infectious diseases.

Epstein-Barr virus–induced gene 3 (EBI3) is a subunit common to IL-27, IL-35, and IL-39. Here, we explore an intracellular role of EBI3 that is independent of its function in cytokines. EBI3-deficient naive CD4(+) T cells had reduced IFN-γ production and failed to induce T cell–dependent colitis in mice. Similarly reduced IFN-γ production was observed in vitro in EBI3-deficient CD4(+) T cells differentiated under pathogenic Th17 polarizing conditions with IL-23. This is because the induction of expression of one of the IL-23 receptor (IL-23R) subunits, IL-23Rα, but not another IL-23R subunit, IL-12Rβ1, was selectively decreased at the protein level, but not the mRNA level. EBI3 augmented IL-23Rα expression via binding to the chaperone molecule calnexin and to IL-23Rα in a peptide-dependent manner, but not a glycan-dependent manner. Indeed, EBI3 failed to augment IL-23Rα expression in the absence of endogenous calnexin. Moreover, EBI3 poorly augmented the expression of G149R, an IL-23Rα variant that protects against the development of human colitis, because binding of EBI3 to the variant was reduced. Taken together with the result that EBI3 expression is inducible in T cells, the present results suggest that EBI3 plays a critical role in augmenting IL-23Rα protein expression via calnexin under inflammatory conditions.

Interleukin (IL)-27, a member of the IL-6/IL-12 heterodimeric cytokine family, induces pro-inflammatory responses including early T helper (Th)1 differentiation and generation of cytotoxic T lymphocytes, and also anti-inflammatory responses including the differentiation to IL-10-producing regulatory T cells, inhibition of Th2 and Th17 differentiation, and suppression of pro-inflammatory cytokine production. Nitric oxide (NO) is a potent source of reactive nitrogen species that play an important role in killing intracellular pathogens and forms a crucial component of host defense. Inducible NO synthase (iNOS), which catalyzes the production of NO, is induced by a range of stimuli including cytokines and microbes. Recently, IL-27 was reported to play an anti-inflammatory role in microglia by blocking oncostatin M-induced iNOS expression and neuronal toxicity. In the present study, we investigated the effects of IL-27 on NO production in thioglycollate-elicited peritoneal macrophages. IL-27 together with lipopolysaccharide (LPS) induced morphological change into more spread and elongated cells and synergistically enhanced NO production. The combined stimulation also enhanced iNOS mRNA expression and the NO production was abrogated by an iNOS inhibitor, NG-monomethyl L-arginine. The synergistic NO production could be attributed to the augmented Toll-like receptor (TLR)4 mRNA expression by the combination. Signal transducer and activator of transcription (STAT)1 was indispensable for the morphological change and NO production. The combination induced nuclear factor κB (NF-κB) translocation into nuclear and phosphorylation of extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK), and their inhibitors suppressed NO production. These results suggest that in contrast to the anti-proinflammatory role in microglia, IL-27 exerts a pro-inflammatory role by enhancing NO production in peritoneal macrophages stimulated with LPS through activation of STAT1, NF-κB and MAPKs.

The interleukin (IL)-6/IL-12 family cytokines have pleiotropic functions and play critical roles in multiple immune responses. This cytokine family has very unique characteristics in that they comprise two distinct subunits forming a heterodimer and each cytokine and receptor subunit shares with each other. The members of this cytokine family are increasing; currently, there are more than six cytokines, including the tentatively named cytokines IL-Y (p28/p40), IL-12 (p35/p40), IL-23 (p19/p40), IL-27 [p28/Epstein–Barr virus-induced protein 3 (EBI3)], IL-35 (p35/EBI3), and IL-39 (p19/EBI3). This family of cytokines covers a very broad range of immune responses, including pro-inflammatory responses, such as helper T (Th)1, Th2, and Th17, to anti-inflammatory responses, such as regulatory T (Treg) cells and IL-10-producing Treg cells. IL-12 is the first member of this family, and IL-12, IL-23, and IL-27 are mainly produced by activated antigen-presenting cells, such as dendritic cells and macrophages. IL-12 plays a critical role in the promotion of Th1 immune responses by inducing interferon-γ production to combat pathogens and malignant tumors. IL-23 induces IL-17 production and is necessary to maintain pathogenic Th17 cells that cause inflammatory and autoimmune diseases. IL-27 was initially reported to play a critical role in promotion of Th1 differentiation; however, subsequent studies revealed that IL-27 has broader stimulatory and inhibitory roles by inducing IL-10-producing Treg cells. IL-35 is produced by forkhead box P3+ Treg cells and activated B cells and has immunosuppressive functions to maintain immune tolerance. The most recently identified cytokine, IL-39, is produced by activated B cells and has pro-inflammatory functions. The cytokine tentatively named IL-Y seems to have anti-inflammatory functions by inhibiting Th1 and Th17 differentiation. In addition, individual cytokine subunits were also shown to have self-standing activities. Thus, promiscuity within the IL-6/IL-12 family cytokines complicates structural and functional clarification and assignment of individual cytokines. A better understanding of the recent advances and expanding diversity in molecular structures and functions of the IL-6/IL-12 family cytokines could allow the creation of novel therapeutic strategies by using them as tools and targeted molecules.

IL-23 plays a critical role in the expansion of highly proinflammatory Th17 cells secreting IL-17 and IL-22. Recently, we demonstrated that Notch signaling drives IL-22 secretion through the aryl hydrocarbon receptor (AHR) and plays a protective role in Con A-induced hepatitis. In this study, we investigated the role of IL-23 in hepatitis using IL-23p19- and IL-17-deficient mice. In WT mice, the injection of Con A induced the upregulation of various cytokines, which included IL-23, IL-22, IL-17, IFN-γ and TNF-α. In IL-23p19-deficient mice, exacerbated hepatitis was observed and serum IL-22 and IL-17 levels were greatly reduced, whereas in IL-17-deficient mice, ameliorated hepatitis was observed. The injection of exogenous IL-22 protected p19-deficient mice from hepatitis, whereas the injection of exogenous IL-23 significantly increased the serum levels of not only IL-22 but also IL-17, and less effectively protected against hepatitis in IL-17-dependent and -independent manners. Finally, it was revealed that STAT3, STAT4 and Notch contributed to the production of both the cytokines, and that the AHR was important only for IL-22 production in response to Con A and IL-23 in liver mononuclear cells. These results suggest that IL-23 plays a protective role in hepatitis through IL-22 production and also a pathological role via IL-17-dependent and -independent mechanisms.

The receptor activator of NF-κB ligand (RANKL), which is expressed by not only osteoblasts but also activated T cells, plays an important role in bone-destructive diseases such as rheumatoid arthritis. IL-27, a member of the IL-6/IL-12 family cytokines, activates STAT1 and STAT3, promotes early helper T (Th)1 differentiation and generation of IL-10-producing type 1 regulatory T (Tr1) cells, and suppresses the production of inflammatory cytokines and inhibits Th2 differentiation. In addition, IL-27 was recently demonstrated to not only inhibit Th17 differentiation but also directly act on osteoclast precursor cells and suppress RANKL-mediated osteoclastogenesis through STAT1-dependent inhibition of c-Fos, leading to amelioration of the inflammatory bone destruction. In the present study, we investigated the effect of IL-27 on the expression of RANKL in CD4(+) T cells. We found that IL-27 greatly inhibits cell surface expression of RANKL on naive CD4(+) T cells activated by T cell receptor ligation and secretion of its soluble RANKL as well. The inhibitory effect was mediated in part by STAT3 but not by STAT1 or IL-10. In contrast, in differentiated Th17 cells, IL-27 much less efficiently inhibited the RANKL expression after restimulation. Taken together, these results indicate that IL-27 greatly inhibits primary RANKL expression in CD4(+) T cells, which could contribute to the suppressive effects of IL-27 on the inflammatory bone destruction.

Cytotoxic T lymphocytes (CTLs) play a critical role in the control of various cancers and infections, and therefore the molecular mechanisms of CTL generation are a critical issue in designing antitumor immunotherapy and vaccines which augment the development of functional and long-lasting memory CTLs. Interleukin (IL)-27, a member of the IL-6/IL-12 heterodimeric cytokine family, acts on naiveCD4+T cells and plays pivotal roles as a proinflammatory cytokine to promote the early initiation of type-1 helper differentiation and also as an antiinflammatory cytokine to limit the T cell hyperactivity and production of pro-inflammatory cytokines. Recent studies revealed that IL-27 plays an important role inCD8+T cells as well. Therefore, this article reviews current understanding of the role of IL-27 inCD8+T cell functions and generation of CTLs.

Cancer is a complex disease with interactions between normal and neoplastic cells. Since current therapies for cancer largely rely on drugs or radiation that kill dividing cells or block cell division, these treatments may have severe side effects on normal proliferating cells in patients with cancer. Therefore, the potential for treatment of cancer patients by immunologic approaches, which may be specific for tumors and will not injure most normal cells, has great promise. Cancer immunotherapy aims to augment the weak host immune response to developing tumors. One strategy is to utilize cytokines such as IL-2. More recently, several exciting new interleukins have been characterized that have considerable promise for future immunotherapy. The promise of cancer immunotherapy largely depends upon the identification of these novel interleukins. This review provides an overview of the antitumor effects of relatively new interleukins as potential therapeutic agents applicable for cancer immunotherapy.

Cancer immunotherapies such as sipuleucel-T and ipilimumab are promising new treatments that harness the power of the immune system to fight cancer and achieve long-lasting remission. Interleukin (IL)-27, a member of the IL-12 heterodimeric cytokine family, has pleiotropic functions in the regulation of immune responses with both pro-inflammatory and anti-inflammatory properties. Evidence obtained using a variety of preclinical mouse models indicates that IL-27 possesses potent antitumor activity against various types of tumors through multiple mechanisms without apparent adverse effects. These mechanisms include those mediated not only by CD8(+) T cells, natural killer cells and macrophages, but also by antibody-dependent cell-mediated cytotoxicity, antiangiogenesis, direct antiproliferative effects, inhibition of expression of cyclooxygenase-2 and prostaglandin E2 , and suppression of epithelial-mesenchymal transition, depending on the characteristics of individual tumors. However, the endogenous role of IL-27 subunits and one of its receptor subunits, WSX-1, in the susceptibility to tumor development after transplantation of tumor cell lines or endogenously arising tumors seems to be more complicated. IL-27 functions as a double-edged sword: IL-27 increases IL-10 production and the expression of programmed death ligand 1 and T-cell immunoglobulin and mucin domain-3, and promotes the generation of regulatory T cells, and IL-27 receptor α singling enhances transformation; IL-27 may augment protumor effects as well. Here, we review both facets of IL-27, antitumor effects and protumor effects, and discuss the potential clinical application of IL-27 as an antitumor agent.

Interleukin (IL)-27 is a multifunctional cytokine that belongs to the IL-6/IL-12 family and has potent antitumor activity through various mechanisms. Our novel findings indicate that IL-27 directly acts on hematopoietic stem cells and promotes their expansion and differentiation into myeloid progenitors to control infection and to eradicate tumors.

Since we first reported the antitumor efficacy of IL-27 in 2004, accumulating evidence obtained by several groups using a variety of preclinical mouse models indicates that IL-27 possesses potent antitumor activity against various types of tumors through multiple mechanisms depending on the characteristics of individual tumors without apparent adverse effects.

Tyrosine kinase inhibitors have dramatically improved the treatment of chronic myeloid leukemia. Recent evidence revealed that some patients with chronic myeloid leukemia can stop imatinib without relapse after achieving a complete molecular response. This review discusses the possible predictive markers to identify these patients who can stop imatinib without relapse.

IL-27, a member of the IL-6/IL-12 family of cytokines, induces early helper T (Th)1 differentiation and generation of cytotoxic T cells and IL-10-producing type 1 regulatory T cells, while it suppresses the production of inflammatory cytokines and inhibits Th2 and Th17 differentiation [1,2]. The receptor activator of NF-kB ligand (RANKL), which is expressed by not only osteoblasts but also activated T cells, plays an important role in bone-destructive disease rheumatoid arthritis (RA). Recently, IL-17-producing Th17 cells were identified as the exclusive osteoclastogenic T-cell subset. This is because Th17 cells express RANKL, and that IL-17 not only induces RANKL expression on osteoblasts, but also increases the production of various inflammatory molecules. It was previously reported that IL-27 is detected in RA synovial membranes and that treatment with IL-27 attenuated inflammatory responses in collagen-induced arthritis (CIA), one of mouse RA models. We have been investigating the role of IL-27 in the regulation of inflammatory responses leading to the development of bone destructive autoimmune disease. We first demonstrated that osteoclastogenesis from bone marrow cells induced by soluble RANKL is inhibited by IL-27 with reduced multinucleated cell numbers [3]. Then, other group further clarified that IL-27 directly acts on osteoclast precursor cells and suppresses RANKL-mediated osteoclastogenesis through STAT1-dependent inhibition of c-Fos, leading to amelioration of the inflammatory bone destruction. We recently investigated the mechanistic role of IL-27 in the pathogenesis of CIA and found that local injection of adenoviral IL-27 transcript into the ankles of CIA mice attenuates joint inflammation, synovial lining thickness, bone erosion and leukocyte migration [4]. IL-27 reduced the production of IL-1b and IL-6, and suppressed Th17 cell differentiation as well as IL-17 downstream target genes, which leads to decreased IL-17-mediated monocyte recruitment and angiogenesis possibly through the reduction of neutrophil and monocyte chemokines. We also elucidated that IL-27 inhibits cell surface expression of RANKL on naive CD4+ T cells activated by T cell receptor ligation and secretion of its soluble RANKL as well [5]. The inhibitory effect was mediated in part by STAT3 but not by STAT1 or IL-10. In differentiated Th17 cells, IL-27 much less but significantly inhibited the RANKL expression after re-stimulation. Taken together, these results suggest that IL-27 regulates inflammatory immune responses leading to the development of bone destructive autoimmune disease through multiple mechanisms as described above (Figure ​(Figure1),1), and that IL-27 may be a promising target for therapeutic intervention to control disease in RA patients. Figure 1 IL-27 regulates inflammatory immune responses leading to the development of bone destructive autoimmune disease RA through multiple mechanisms.