A line of nonobese diabetic (NOD) mice expressing the human diabetes-associated HLA-DQ8 transgene in the absence of mouse IA␤ failed to show spontaneous insulitis or diabetes, but rather developed dilated cardiomyopathy, leading to early death from heart failure. Pathology in these animals results from an organ-and cell-specific autoimmune response against normal cardiomyoctes in the atrial and ventricular walls, as well as against very similar myocytes present in the outermost muscle layer surrounding the pulmonary veins. Progression of the autoimmune process could be followed by serial ECG measurements; irradiation of young animals significantly delayed disease progression, and this effect could be reversed by adoptive transfer of splenocytes taken from older animals with complete heart block. Disease progression could also be blocked by cyclosporin A treatment, but was accelerated by injection of complete Fruend's adjuvant. The constellation of findings of spontaneously arising destructive focal lymphocytic infiltrates within the myocardium, rising titers of circulating anticardiac autoantibodies, dilation of the cardiac chambers, and gradual progression to end-stage heart failure bears a striking resemblance to what is seen in humans with idiopathic dilated cardiomyopathy, a serious and often life-threatening medical condition. This transgenic strain provides a highly relevant animal model for human autoimmune myocarditis and postinflammatory dilated cardiomyopathy.I diopathic dilated cardiomyopathy (IDCM) describes a condition whereby previously healthy individuals develop lifethreatening heart failure associated with enlargement of the heart, but with no apparent underlying cause (1, 2). The cardiac pathology seen in the majority of IDCM patients indicates a recent or more long-standing immune-mediated inflammatory process within the muscle tissue of the heart (i.e., myocarditis) (3,4). IDCM patients often demonstrate circulating anticardiac autoantibodies, and the myocarditis is generally thought to arise from an autoimmune response against cardiac tissues (5). Research on IDCM has been hampered by the lack of an appropriate animal model, that is, a model where animals develop disease spontaneously, show severe life-threatening pathology, and display an immunological and histological picture similar to that seen in humans with IDCM.The human MHC class II molecule DQ8 (i.e., haplotype DQA1*0301, DQB1*0302) is known to be associated with type 1 diabetes (T1D). To map DQ8-restricted T cell epitopes for T1D autoantigens we crossed DQ8 transgenic nonobese diabetic (NOD) mice with a NOD MHC class II ␤-chain knockout line (6). Because the resulting animals express the human MHC class II molecule but not the mouse, any CD4 ϩ T cells arising would be restricted to the human MHC molecule. We chose the NOD strain because it is known to have defects in self-tolerance, which we hypothesized would aid our efforts to induce immune responses against self-antigens such as GAD65. Although replacement of the murine T1D-asso...

In humans, spontaneous autoimmune attack against cardiomyocytes often leads to idiopathic dilated cardiomyopathy (IDCM) and life-threatening heart failure. HLA-DQ8 transgenic IAb knockout NOD mice (NOD.DQ8/Ab0; DQA1*0301, DQB1*0302) develop spontaneous anticardiomyocyte autoimmunity with pathology very similar to human IDCM, but why the heart is targeted is unknown. In the present study, we first investigated whether NOD/Ab0 mice transgenic for a different DQ allele, DQ6, (DQA1*0102, DQB1*0602) would also develop myocarditis. NOD.DQ6/Ab0 animals showed no cardiac pathology, implying that DQ8 is specifically required for the myocarditis phenotype. To further characterize the cellular immune mechanisms, we established crosses of our NOD.DQ8/Ab0 animals with Rag1 knockout (Rag10), Ig H chain knockout (IgH0), and β2-microglobulin knockout (β2m0) lines. Adoptive transfer of purified CD4 T cells from NOD.DQ8/Ab0 mice with complete heart block (an indication of advanced myocarditis) into younger NOD.DQ8/Ab0 Rag10 animals induced cardiac pathology in all recipients, whereas adoptive transfer of purified CD8 T cells or B lymphocytes had no effect. Despite the absence of B lymphocytes, NOD.DQ8/Ab0IgH0 animals still developed complete heart block, whereas NOD.DQ8/Ab0β2m0 mice (which lack CD8 T cells) failed to develop any cardiac pathology. CD8 T cells (and possibly NK cells) seem to be necessary to initiate disease, whereas once initiated, CD4 T cells alone can orchestrate the cardiac pathology, likely through their capacity to recruit and activate macrophages. Understanding the cellular immune mechanisms causing spontaneous myocarditis/IDCM in this relevant animal model will facilitate the development and testing of new therapies for this devastating disease.

Carcinoma derived TGF-β acts as a potent pro-oncogenic factor and suppresses antitumor immunity. To antagonize TGF-β–mediated effects in tandem with a proinflammatory immune stimulus, we generated a chimeric protein borne of the fusion of IL-2 and the soluble extracellular domain of TGF-βR II (FIST). FIST acts as a decoy receptor trapping active TGF-β in solution and interacts with IL-2–responsive lymphoid cells, inducing a distinctive hyperactivation of STAT1 downstream of IL-2R, which in turn promotes SMAD7 overexpression. Consequently, FIST-stimulated lymphoid cells are resistant to TGF-β–mediated suppression and produce significant amounts of proinflammatory cytokines. STAT1 hyperactivation further induces significant secretion of angiostatic CXCL10. Moreover, FIST upregulates T-bet expression in NK cells promoting a potent Th1-mediated antitumor response. As a result, FIST stimulation completely inhibits pancreatic cancer (PANC02) and melanoma (B16) tumor growth in immunocompetent C57BL/6 mice. In addition, melanoma cells expressing FIST fail to form tumors in CD8−/−, CD4−/−, B cell-deficient (μMT), and beige mice, but not in NOD-SCID and Rag2/γc knockout mice, consistent with the pivotal role of FIST-responsive, cancer-killing NK cells in vivo. In summary, FIST constitutes a novel strategy of treating cancer that targets both the host’s angiogenic and innate immune response to malignant cells.

Natural killer (NK) cells are appealing cellular pharmaceuticals for cancer therapy because of their innate ability to recognize and kill tumor cells. Therefore, the development of methods that can enhance the potency in their anticancer effect would be desirable. We have previously shown that a murine granulocyte macrophage colony-stimulating factor (GM-CSF)/interleukin 2 (IL-2) fusion protein displays novel antitumor properties in vivo compared with both cytokines in combination due to recruitment of NK cells. In the present work, we have found that human ortholog of the GM-CSF/IL-2 fusion protein (a.k.a. hGIFT2) induces robust NK cell activation ex vivo with significant secretion of RANTES and a 37-fold increase in IFNγ production when compared with either IL-2 or GM-CSF single cytokine treatment or their combination. Moreover, hGIFT2 upregulates the expression of NK cell activating receptors NKp44, NKp46, and DNAM-1 (CD226), as well as CD69, CD107a, and IL-2Rβ expression. In addition, hGIFT2 promotes NK cell maturation, based on the downregulation of CD117 expression and upregulation of CD11b. This phenotype correlates with significantly greater cytotoxicity against tumor cells. At the molecular level, hGIFT2 leads to a potent activation of Janus-activated kinases (JAK) downstream of both IL-2 and GM-CSF receptors (JAK1 and JAK2, respectively) and consequently leads to a hyperphosphorylation of signal transducers and activators of transcription (STAT)1, STAT3, and STAT5. In conclusion, hGIFT2 fusokine possesses unique biochemical properties distinct from IL-2 and GM-CSF, constitutes a novel and potent tool for ex vivo NK cell activation and maturation, and may be of use for cancer cell immunotherapy. [Cancer Res 2009;69(23):9020-8]