Therapeutic potential of interleukin-27 against cancers in preclinical mouse models

Regulation of myelopoiesis by proinflammatory cytokines in infectious diseases

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.

Protective effects against tumors and infection by interleukin-27 through promotion of expansion and differentiation of hematopoietic stem cells into myeloid progenitors

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.

Interleukin-27 Exerts Its Antitumor Effects by Promoting Differentiation of Hematopoietic Stem Cells to M1 Macrophages

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.

Expanding Diversity in Molecular Structures and Functions of the IL-6/IL-12 Heterodimeric Cytokine Family

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.