Mingli Xu

Regulation of Antitumor Immune Responses by the IL-12 Family Cytokines, IL-12, IL-23, and IL-27

The interleukin (IL)-12 family, which is composed of heterodimeric cytokines including IL-12, IL-23, and IL-27, is produced by antigen-presenting cells such as macrophages and dendritic cells and plays critical roles in the regulation of helper T (Th) cell differentiation. IL-12 induces IFN-γ production by NK and T cells and differentiation to Th1 cells. IL-23 induces IL-17 production by memory T cells and expands and maintains inflammatory Th17 cells. IL-27 induces the early Th1 differentiation and generation of IL-10-producing regulatory T cells. In addition, these cytokines induce distinct immune responses to tumors. IL-12 activates signal transducers and activator of transcription (STAT)4 and enhances antitumor cellular immunity through interferon (IFN)-γ production. IL-27 activates STAT1, as does IFN-γ and STAT3 as well, and enhances antitumor immunity by augmenting cellular and humoral immunities. In contrast, although exogenously overexpressed IL-23 enhances antitumor immunity via memory T cells, endogenous IL-23 promotes protumor immunity through STAT3 activation by inducing inflammatory responses including IL-17 production.

Pivotal Roles of T-Helper 17-Related Cytokines, IL-17, IL-22, and IL-23, in Inflammatory Diseases

T-helper 17 (Th17) cells are characterized by producing interleukin-17 (IL-17, also called IL-17A), IL-17F, IL-21, and IL-22 and potentially TNF-α and IL-6 upon certain stimulation. IL-23, which promotes Th17 cell development, as well as IL-17 and IL-22 produced by the Th17 cells plays essential roles in various inflammatory diseases, such as experimental autoimmune encephalomyelitis, rheumatoid arthritis, colitis, and Concanavalin A-induced hepatitis. In this review, we summarize the characteristics of the functional role of Th17 cells, with particular focus on the Th17 cell-related cytokines such as IL-17, IL-22, and IL-23, in mouse models and human inflammatory diseases.

A pivotal role for interleukin-27 in CD8+ T cell functions and generation of cytotoxic T lymphocytes.

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 naive CD4+ 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 in CD8+ T cells as well. Therefore, this article reviews current understanding of the role of IL-27 in CD8+ T cell functions and generation of CTLs.

USP15 plays an essential role for caspase-3 activation during Paclitaxel-induced apoptosis.

Paclitaxel (also known as Taxol) is a well-known anticancer agent that blocks cell mitosis and kills tumor cells, and is often used in clinic to treat cancers. Despite the success of Paclitaxel, the development of drug resistance prevents its clinical applicability. Here, we screened an siRNA library against the entire human genomes using HeLa cells, and have find that lack of USP15 (ubiquitin-specific protease 15) causes Paclitaxel resistance. We also observed the decreased expression of USP15 in Paclitaxel-resistant human ovarian cancer samples. In addition, we have demonstrated that USP15 plays an essential role for stability and activity of caspase-3 during Paclitaxel-induced apoptosis. Thus, USP15 may be a candidate diagnostic marker and therapeutic target for Paclitaxel-resistant cancers.

Regulation of the development of acute hepatitis by IL-23 through IL-22 and IL-17 production.

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.

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.

Potential clinical application of interleukin-27 as an antitumor agent

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.

Interleukins and cancer immunotherapy

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.

Identification of a novel role of Septin 10 in paclitaxel-resistance in cancers through a functional genomics screen

Paclitaxel (also known as taxol) is a member of the taxane class of anticancer agents, which has a well‐known mechanism that blocks cell mitosis and kills tumor cells, that is often used in clinics to treat cancer. However, some carcinomas such as breast, ovarian and non‐small‐cell lung cancers are often resistant to paclitaxel treatment. In this study, we used a lentiviral siRNA library against the entire human genomes to identify genes associated with sensitivity to paclitaxel. We isolated two paclitaxel‐resistant clones carrying the siRNA specific to septin 10 (SEPT10) and to budding uninhibited by benzimidazoles 3. The relation of budding uninhibited by benzimidazoles 3 to paclitaxel sensitivity has already been established, but that of SEPT10 remains unknown. Interestingly, overexpression of SEPT10 increased cells’ sensitivity to paclitaxel; we also found that SEPT10 is an important regulator for microtubule stability. Furthermore, we found that paclitaxel‐resistant tumors had decreased expression of SEPT10. Thus, SEPT10 may be a novel candidate molecule that acts as a good indicator of paclitaxel‐resistant carcinomas (Cancer Sci 2012; 103: 821–827)

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

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.