Based on the evidence that IL-17 is a key cytokine involved in various inflammatory diseases, we explored the critical role of IL-17-producing cd T cells for tumor development in tumor-bearing mouse model. IL-17 À/À mice exhibited a significant reduction of tumor growth, concomitantly with the decrease of vascular density at lesion area, indicating a pro-tumor property of IL-17. Among tumor-infiltrating lymphocytes (TIL), cd T cells were the major cellular source of IL-17. Analysis of TCR repertoires in TIL-cd T cells showed that circulating cd T cells, but not skin resident Vc5 1 cd T cells, produced IL-17. Neutralizing antibodies against IL-23, IL-6, and TGF-b, which were produced within the tumor microenvironment, inhibited the induction of IL-17-producing cd T cells. IL-17 production by tumor-infiltrating cd T cells was blocked by anti-cdTCR or anti-NKG2D antibodies, indicating that these ligands, expressed within the tumor microenvironment, are involved in cd T-cell activation. The IL-17-producing TIL-cd T cells exhibited reduced levels of perforin mRNA expression, but increased levels of COX-2 mRNA expression. Together, our findings support the novel concept that IL-17-producing cd T cells, generated in response to tumor microenvironment, act as tumor-promoting cells by inducing angiogenesis. IntroductionIn order to understand how tumor cells can escape immune surveillance mechanisms and thus develop anti-tumor therapies, it is critically important to investigate the mechanisms by which the immune system interacts with the tumor microenvironment. The tumor microenvironment, which is mainly composed of tumor cells, stromal cells, and tumor-infiltrating immune cells, is entirely different from noncancerous tissues. This unique microenvironment potently inhibits immune responses against tumor cells via various soluble mediators and contact-dependent mechanisms [1,2]. Previously, it was suggested that T-cell Eur. J. Immunol. 2010. 40: 1927-1937 DOI 10.1002 Cellular immune response 1927 responses within the local tumor tissue are completely inhibited. However, this concept was abandoned following the discovery of the regulatory T-cell and Th17 cell subsets, which are activated rather than suppressed in the tumor microenvironment via TGF-b and/or IL-6. Thus, the tumor microenvironment is conducive to IL-17 production. In fact, it has been shown that IL-17 is produced in human and murine tumor tissues [3][4][5]. Tumor cells promote neo-vascularization into tumor tissues through hyperproduction of angiogenic factors, which also support their own abnormal proliferation and survival [6]. It has been reported that tumor cells over-expressing IL-17 significantly promote new vessel growth into the tumor tissues [5]; however, physiological effects of IL-17 on tumor progression remain to be defined. Th17 differentiation from naïve CD4 1 T cells is regulated by TGF-b and IL-6. Proliferation, maintenance and full maturation of these cells are controlled by . Recently, it has been shown that IL-17 is produced by diverse T...

Radiation therapy is one of the primary treatment modalities for cancer along with chemotherapy and surgical therapy. The main mechanism of the tumor reduction after irradiation has been considered to be damage to the tumor DNA. However, we found that tumor-specific CTL, which were induced in the draining lymph nodes (DLN) and tumor tissue of tumor-bearing mice, play a crucial role in the inhibition of tumor growth by radiation. Indeed, the therapeutic effect of irradiation was almost completely abolished in tumor-bearing mice by depleting CD8 + T cells through anti-CD8 monoclonal antibody administration. In mice whose DLN were surgically ablated or genetically defective (Aly/Aly mice), the generation of tetramer + tumor-specific CTL at the tumor site was greatly reduced in parallel with the attenuation of the radiation-induced therapeutic effect against the tumor. This indicates that DLN are essential for the activation and accumulation of radiationinduced CTL, which are essential for inhibition of the tumor. A combined therapy of local radiation with Th1 cell therapy augmented the generation of tumor-specific CTL at the tumor site and induced a complete regression of the tumor, although radiation therapy alone did not exhibit such a pronounced therapeutic effect. Thus, we conclude that the combination treatment of local radiation therapy and Th1 cell therapy is a rational strategy to augment antitumor activity mediated by tumor-specific CTL.

We propose a novel role for interleukin (IL) 6 in inducing rapid spontaneous proliferation (SP) of naive CD8 + T cells, which is a crucial step in the differentiation of colitogenic CD8 + T cells. Homeostasis of T cells is regulated by two distinct modes of cell proliferation: major histocompatibility complex/antigen -driven rapid SP and IL-7/IL-15 -dependent slow homeostatic proliferation. Using our novel model of CD8 + T cell -dependent colitis, we found that SP of naive CD8 + T cells is essential for inducing pathogenic cytokine-producing effector T cells. The rapid SP was predominantly induced in mesenteric lymph nodes (LNs) but not in peripheral LNs under the infl uence of intestinal fl ora and IL-6. Indeed, this SP was markedly inhibited by treatment with anti -IL-6 receptor monoclonal antibody (IL-6R mAb) or antibiotic-induced fl ora depletion, but not by anti -IL-7R mAb and/or in IL-15 -defi cient conditions. Concomitantly with the inhibition of SP, anti -IL-6R mAb signifi cantly inhibited the induction of CD8 + T cell -dependent autoimmune colitis. Notably, the transfer of naive CD8 + T cells derived from IL-17 ؊ / ؊ mice did not induce autoimmune colitis. Thus, we conclude that IL-6 signaling is crucial for SP under lymphopenic conditions, which subsequently caused severe IL-17 -producing CD8 + T cell -mediated autoimmune colitis. We suggest that anti -IL-6R mAb may become a promising strategy for the therapy of colitis.

Objective Kawasaki disease (KD) is the most common cause of acquired cardiac disease in US children. In addition to coronary artery abnormalities and aneurysms, it can be associated with systemic arterial aneurysms. We evaluated the development of systemic arterial dilatation and aneurysms, including abdominal aortic aneurysm (AAA) in the Lactobacillus casei cell wall extract (LCWE)-induced KD vasculitis mouse model. Methods and Results We discovered that in addition to aortitis, coronary arteritis and myocarditis, the LCWE-induced KD mouse model is also associated with abdominal aorta dilatation and AAA, as well as renal and iliac artery aneurysms. AAA induced in KD mice was exclusively infrarenal, both fusiform and saccular, with intimal proliferation, myofibroblastic proliferation, break in the elastin layer, vascular smooth muscle cell loss, and inflammatory cell accumulation in the media and adventitia. Il1r−/−, Il1a−/−, and Il1a−/− mice were protected from KD associated AAA. Infiltrating CD11c+ macrophages produced active caspase-1 and caspase-1 or NLRP3 deficiency inhibited AAA formation. Treatment with IL-1R antagonist (Anakinra), anti-IL-1α, or anti-IL-1β mAb blocked LCWE-induced AAA formation. Conclusions Similar to clinical KD, the LCWE-induced KD vasculitis mouse model can also be accompanied by AAA formation. Both IL-1α and IL-1β play a key role, and that use of an IL-1R blocking agent that inhibits both pathways may be a promising therapeutic target not only for KD coronary arteritis, but also for the other systemic arterial aneurysms including AAA that maybe seen in severe cases of KD. The LCWE-induced vasculitis model may also represent an alternative model for AAA disease.

Objective Kawasaki disease (KD) is the most common cause of acute vasculitis and acquired cardiac disease among US children. We have previously shown that both TLR2/MyD88 and IL-1β signaling are required for the Lactobacillus casei cell wall extract (LCWE)-induced KD vasculitis mouse model. The objectives of this study were to investigate the cellular origins of IL-1 production, the role of CD11c+ Dendritic Cells (DCs) and macrophages and the relative contribution of hematopoietic and stromal cells for IL-1 responsive cells, as well the MyD88 signaling in LCWE-induced KD mouse model of vasculitis. Approach and Results Using mouse knockout models as well as antibody depletion, we found that both IL-1α and IL-1β were required for LCWE-induced KD. Both DCs and macrophages were necessary and we found that MyD88 signaling was required in both hematopoietic and stromal cells. However, IL-1 response and signaling was critically required in non-endothelial stromal cells, but not hematopoietic cells. Conclusions Our results suggest that IL-1α and IL-1β as well as CD11c+ DCs and macrophages are essential for the development of KD vasculitis and coronary arteritis in this mouse model. Bone marrow chimera experiments suggest that MyD88 signaling is important in both hematopoietic and stromal cells, while IL-1 signaling and response is required only in stromal cells, but not in endothelial cells. Determining the role IL-1α and IL-1β and of specific cell types in the KD vasculitis mouse model may have important implications for the design of more targeted therapies and understanding of the molecular mechanisms of KD immunopathologies.

CD11b+ Gr-1 + immature myeloid cells (

The discovery of a large array of tumor antigens has demonstrated that host lymphocytes can indeed recognize and destroy tumor cells as originally proposed in the cancer immunosurveillance hypothesis. Recent reports that led to the cancer immunoediting concept also strongly support the immunosurveillance hypothesis, and they further indicate that the host immune system plays a critical role not only in promoting host protection against cancer but also in selecting tumors that can better escape from immune attack. Thus, it is now clear that T cells have the ability to recognize and destroy spontaneously arising tumors. However, the generation of antitumor immunity is often difficult in the tumor-bearing host because of various negative regulatory mechanisms. Here, we review our recent work on tumor immunotherapy, which utilizes the activation of type-1 innate and/or acquired immunity as a potent strategy to overcome immunosuppression in the tumor-bearing host. We have established a variety of tumor therapeutic protocols that aim to activate type-1 immunity, such as tumor-vaccine therapy with CpG encapsulated in liposomes, cell therapy using tumor-specific Th1 cells, and gene therapy using gene-engineered Th1 cells. We found that CpG encapsulated in liposomes stimulated IL-12-producing DC and induced IFN-γ γ γ γ-producing NK cells, NKT cells, and tumorspecific CTL. Th1 cell therapy was also shown to be beneficial for acceleration of APC/Th1 cell-cell interaction in the DLN, which was critical for inducing tumor-specific CTL at the tumor site. Therefore, we conclude that the activation of type-1 innate and acquired immunity is crucial for tumor immunotherapy in order to overcome strong immunosuppression in the tumor-bearing host. (Cancer Sci 2004; 95: 697-703) ince the cancer immunosurveillance hypothesis was proposed by Ehrlich, Burnet, and Thomas, 1, 2) tumor immunologists have asked whether the host immune system can prevent tumor growth. Recent reports from several groups have re-addressed this issue and provided strong evidence for the existence of an effective cancer immunosurveillance process in mice.3-11) As summarized in Table 1, mice lacking specific cellular populations, such as T cells, natural killer T (NKT) cells, and/or natural killer (NK) cells, as well as specific molecules, such as interferon (IFN)-γ, interleukin (IL)-12, perforin, or tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), unequivocally show higher incidences of tumor development. Moreover, administration of IL-12 or α-galactosylceramide (α-GalCer) that can stimulate T, NKT, and/or NK cells, reduces primary tumor incidence.Although it is much more difficult to address cancer immunosurveillance in humans, three lines of evidence suggest that cancer immunosurveillance indeed occurs in humans: (i) immunosuppressed transplant recipients display higher incidences of non-viral tumors, such as melanomas, colon, lung, pancreas, bladder, kidney, and endocrine system cancers, than agematched immunocompetent control populations, ...

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