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ABSTRACT: Interleukin (IL)-21 is a novel cytokine in clinical development for the treatment of cancer. In this study, we have compared the efficacy of subcutaneous and intratumoral (IT) administration of IL-21 protein in two syngeneic mouse tumor models, RenCa renal cell carcinoma and B16 melanoma, and investigated the mechanisms by which IL-21 enhances CD8 T-cell-mediated antitumor immunity. We found that in comparison to subcutaneous administration, IT administration of IL-21 more potently inhibited tumor growth and increased survival. This correlated with increased densities of tumor-infiltrating CD8 and CD4CD25 T cells, but not CD4CD25FoxP3 T cells. Furthermore, IT administration of IL-21 increased degranulation, and expression of interferon-gamma and granzyme B in tumor-infiltrating CD8 T cells. Tumors injected with IL-21 grew slower than contralateral tumors, suggesting that the increased efficacy of IT administration of IL-21 was due to a local rather than systemic effect. IT administration of IL-21 led to enlarged tumor-draining lymph nodes (LNs), with increased naive lymphocyte numbers and proliferation of activated lymphocytes, suggesting that local administration of IL-21 generally benefits the tumor microenvironment and activates tumor-draining LNs. Overall, our data suggest that IL-21 augments CD8 T-cell-mediated antitumor immunity through increased proliferation and effector function and acts both on tumor-infiltrating CD8 T cells as well as on the draining LNs. IT administration led to superior CD8 T-cell proliferation, effector function, and antitumor efficacy, suggesting that IT administration of IL-21 may be clinically useful in patients with unresectable tumors.
Journal of immunotherapy (Hagerstown, Md.: 1997) 04/2010; 33(3):236-49. · 3.20 Impact Factor
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ABSTRACT: IL-21 has antitumor activity through actions on NK cells and CD8(+) T cells, and is currently in clinical development for the treatment of cancer. However, no studies have addressed the role of endogenous IL-21 in tumor immunity. In this study, we have studied both primary and secondary immune responses in IL-21(-/-) and IL-21R(-/-) mice against several experimental tumors. We found intact immune surveillance toward methylcholanthrene-induced sarcomas in IL-21(-/-) and IL-21R(-/-) mice compared with wild-type mice and B16 melanomas showed equal growth kinetics and development of lung metastases. IL-21R(-/-) mice showed competent NK cell-mediated rejection of NKG2D ligand (Rae1beta) expressing H-2b(-) RMAS lymphomas and sustained transition to CD8(+) T cell-dependent memory against H-2b(+) RMA lymphomas. alpha-Galactosylceramide stimulation showed equal expansion and activation of NKT and NK cells and mounted a powerful antitumor response in the absence of IL-21 signaling, despite reduced expression of granzyme B in NKT, NK, and CD8(+) T cells. Surprisingly, host IL-21 significantly restricted the expansion of Ag-specific CD8(+) T cells and inhibited primary CD8(+) T cell immunity against OVA-expressing EG7 lymphomas, as well as the secondary expansion of memory CD8(+) T cells. However, host IL-21 did not alter the growth of less immunogenic MC38 colon carcinomas with dim OVA expression. Overall, our results show that endogenous IL-21/IL-21R is not required for NK, NKT, and CD8(+) T cell-mediated tumor immunity, but restricts Ag-specific CD8(+) T cell expansion and rejection of immunogenic tumors, indicating novel immunosuppressive actions of this cytokine.
The Journal of Immunology 11/2009; 183(11):7326-36. · 5.79 Impact Factor
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ABSTRACT: Interleukin-21 (IL-21) is a class I cytokine with antitumor properties due to enhanced proliferation and effector function of CD8(+) T cells and natural killer (NK) cells. Here we have explored the magnitude and time-course of cytostatics-induced lymphopenia in mice and investigated whether treatment with cytostatics influences the antitumor effect of IL-21 in mouse tumor models. We show that pegylated liposomal doxorubicin (PLD), irinotecan and oxaliplatin induced transient lymphopenia, whereas 5-fluorouracil (5-FU) transiently increased lymphocyte counts. B cells were more sensitive than T cells towards irinotecan and oxaliplatin. Additive antitumor effects were observed after combining IL-21 with PLD, oxaliplatin and to less extent 5-FU but not irinotecan, and larger effect was observed when IL-21 administration was postponed relative to chemotherapy, suggesting that these agents may transiently impair immune function. However, the chemotherapies did not significantly alter the levels of circulating regulatory T cells and only marginally affected the ability of CD8(+) T cells to respond to IL-21 measured as increased granzyme B mRNA. Our results show that IL-21 therapy can be successfully combined with agents from different chemotherapeutic drug classes, i.e. topoisomerase II inhibitors (PLD), anti-metabolites (5-FU) and platinum analogs (oxaliplatin) provided that IL-21 therapy is delayed relative to chemotherapy.
Cytokine 09/2009; 48(3):231-8. · 3.02 Impact Factor
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Ian D Davis,
Ben Brady,
Richard F Kefford,
Michael Millward,
Jonathan Cebon,
Birte K Skrumsager,
Ulrik Mouritzen,
Lasse Tengbjerg Hansen, Kresten Skak,
Dorthe Lundsgaard,
Klaus Stensgaard Frederiksen,
Paul E G Kristjansen,
Grant McArthur
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ABSTRACT: Human interleukin-21 (IL-21) is a class I cytokine that mediates activation of CD8(+) T cells, natural killer (NK) cells, and other cell types. We report final clinical and biological results of a phase II study of recombinant human IL-21 (rIL-21) in patients with metastatic melanoma.
Open-label, single-arm, two-stage trial. Eligibility criteria: unresectable metastatic melanoma, measurable disease by Response Evaluation Criteria in Solid Tumors, no prior systemic therapy (adjuvant IFN permitted), adequate major organ function, good performance status, no significant autoimmune disease, and life expectancy at least 4 months. Primary objective: antitumor efficacy (response rate). Secondary objectives: safety, blood biomarkers, and generation of anti-rIL-21 antibodies. rIL-21 (30 microg/kg/dose) was administered by intravenous bolus injection in 8-week cycles (5 dosing days followed by 9 days of rest for 6 weeks and then 2 weeks off treatment).
Stage I of the study comprised 14 patients. One confirmed complete response (CR) was observed, and as per protocol, 10 more patients were accrued to stage II (total n = 24: 10 female and 14 male). Best tumor response included one confirmed CR and one confirmed partial response, both with lung metastases. Treatment was overall well tolerated. Biomarker analyses showed increases in serum soluble CD25, frequencies of CD25(+) NK and CD8(+) T cells, and mRNA for IFN-gamma, perforin, and granzyme B in CD8(+) T and NK cells.
rIL-21 administered at 30 microg/kg/d in 5-day cycles every second week is biologically active and well tolerated in patients with metastatic melanoma. Confirmed responses, including one CR, were observed.
Clinical Cancer Research 04/2009; 15(6):2123-9. · 7.74 Impact Factor
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ABSTRACT: For decades cytokines such as type I interferons and IL-2 have been used in immunotherapy against cancer, viral hepatitis, and autoimmune diseases such as multiple sclerosis. However, the therapeutic use of cytokines has been hampered by their pleiotropic effects on target-cells. Thus, cytokines such as IFN-alpha and IL-2 have multiple and severe side effects. Accordingly, they are generally used at sub-optimal doses, which limit their clinical efficacy. Here we hypothesized that a combination of IFN-alpha and IL-21, a novel cytokine of the IL-2 family with anti-cancer effects, will increase the anti-cancer efficacy at sub-optimal cytokine doses. We show that the combined stimulation of target-cells with IFN-alpha and IL-21 triggers an increased STAT3 activation whereas the activation of other STATs including STAT1/2 is unaffected. In parallel, the combined stimulation with IFN-alpha and IL-21 triggers a selective increase in MHC class I expression and NK- and CD8(+) T-cell-mediated cytotoxicity. In an experimental in vivo model of renal carcinoma, the combined treatment of IFN-alpha and IL-21 also produces a significant anti-cancer effect as judged by an inhibition of tumor growth and an increased survival. Taken together our data show that the combined use of IFN-alpha and IL-21 boosts STAT3 signaling, cytotoxicity, and anti-tumor efficacy, suggesting that a combinatorial therapeutic use of these cytokines may benefit cancer patients.
Molecular Immunology 11/2008; 46(5):812-20. · 2.90 Impact Factor
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ABSTRACT: Recombinant interleukin-21 (rIL-21) is an immune stimulating cytokine recently tested in two Phase 1 trials for immune responsive cancers. A secondary objective of these trials was to characterize pharmacodynamic responses to rIL-21 in patients. Here, we report the effects of systemic rIL-21 on serum markers of immune stimulation.
Recombinant IL-21 was administered by intravenous bolus injection at dose levels from 1 to 100 microg/kg using two distinct treatment regimens: thrice weekly ('3/w') for 6 weeks; or once daily for five consecutive days followed by nine dose-free days ('5 + 9'). In the absence of dose limiting toxicity, additional cycles of dosing were initiated immediately following the nine dose-free days. An array of 70 different proteins was profiled in subject serum samples from several time points during the course of the study. Hierarchical clustering analysis was performed on a normalized subset of these data.
Systemic administration of rIL-21 affected the serum levels of several cytokines, chemokines, acute-phase proteins and cell adhesion proteins. The magnitude and duration of response were dose dependent for a subset of these biomarkers. The 5 + 9 dosing regimen generally produced cyclic changes that were of greater magnitude, as compared to a more chronic stimulation with the 3/w dosing regimen. Despite these differences, rIL-21 effects on many analytes were similar between regimens when averaged over the time of treatment. Based on similar temporal, between-subject and dose response changes, groups of analytes were identified that exhibited distinct components of the rIL-21-mediated immune activation. Biomarkers indicative of lymphocyte activation (increased IL-16, decreased RANTES), acute phase response (increased CRP, ferritin), myeloid activation (increased MDC, MIP-1 alpha), and leukocyte chemotaxis/trafficking (increased sCAMs, MCP-1) were strongly modulated in subjects treated with rIL-21.
Administration of rIL-21 resulted in activation of multiple cell types and immune response pathways. The changes observed in serum proteins were consistent with coincident processes of lymphoid and myeloid cell activation and trafficking, and acute phase response.
Cancer Immunology and Immunotherapy 11/2008; 58(6):843-54. · 3.70 Impact Factor
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Klaus Stensgaard Frederiksen,
Dorthe Lundsgaard,
Jeremy A. Freeman,
Steven D. Hughes,
Thomas L. Holm,
Birte K. Skrumsager,
Andreas Petri,
Lasse T. Hansen,
Grant A. McArthur,
Ian D. Davis, Kresten Skak
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ABSTRACT: PurposeHuman interleukin-21 (IL-21) is a class I cytokine previously reported in clinical studies on immune responsive cancers. Here
we report the effects of systemic IL-21 therapy on the immune system in two phase 1 trials with this novel cytokine.
Experimental designRecombinant IL-21 was administered by intravenous bolus injection at dose levels from 1 to 100μg/kg using two planned treatment
regimens: thrice weekly for 6weeks (3/week); or once daily for five consecutive days followed by nine dose-free days (5+9).
The following biomarkers were studied in peripheral blood mononuclear cells (PBMC) during treatment: phosphorylation of STAT3,
alterations in the composition of leukocyte subsets, ex vivo cytotoxicity, expression of effector molecules in enriched CD8+ T cells and CD56+ NK cells by quantitative RT-PCR, and gene array profiling of CD8+ T cells.
ResultsEffects of IL-21 were observed at all dose levels. In the 5+9 regimen IL-21 induced a dose dependent decrease in circulating
NK cells and T cells followed by a return to baseline in resting periods. In both CD8+ T cells and CD56+ NK cells we found up-regulation of perforin and granzyme B mRNA. In addition, full transcriptome analysis of CD8+ T cells displayed changes in several transcripts associated with increased cell cycle progression, cellular motility, and
immune activation. Finally, cytotoxicity assays showed that IL-21 enhanced the ability of NK cells to kill sensitive targets
ex vivo.
ConclusionsIL-21 was biologically active at all dose levels administered with evidence of in vivo NK cell and CD8+ T cell activation.
Cancer Immunology and Immunotherapy 09/2008; 57(10):1439-1449. · 3.70 Impact Factor
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ABSTRACT: Interleukin (IL)-21 is a novel cytokine that has been shown to enhance proliferation and activation of CD8+ T cells, enhance natural killer (NK) cell activity and costimulate anti-CD40-driven B-cell proliferation in mice. Several studies have furthermore demonstrated antitumour effects of IL-21 administration in mouse models. In this study we have investigated how IL-21 affects the survival and cytotoxicity of human NK cells and modulates their expression of surface receptors and of the effector molecules granzyme B and perforin. In contrast to murine NK cells, where IL-21 alone cannot sustain survival, IL-21 and IL-2 were equally efficient in sustaining survival of human NK cells. In the absence of other cytokines, IL-21 had little effect on expression of a panel of surface receptors on human NK cells. However, IL-21 synergized with IL-2 to up-regulate several surface receptors, including NKG2A, CD25, CD86 and CD69. The CD25+ CD86+ NK cells were CD56(bright) and were large and granular. Expression of the effector molecules perforin and granzyme A and B was up-regulated by IL-21 at both mRNA and protein levels. Furthermore, IL-21 increased the cytotoxicity of NK cells against K562 target cells. These findings suggest that IL-21 modulates NK cell activity through induction of intracellular effector molecules as well as modulation of surface receptor expression.
Immunology 05/2008; 123(4):575-83. · 3.32 Impact Factor
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ABSTRACT: In the past 20 years researchers have attempted to activate the host immune defence system to kill tumour cells and eradicate cancer. In some cases, the response of patients to immunotherapy has been extremely successful; however, other trials have shown disappointing results, and so there is a clear need for more effective therapies that can effectively adjunct conventional approaches. Interleukin 21 (IL21) is a new immune-stimulating cytokine that has demonstrated antitumour activity in several preclinical models, and has recently undergone Phase I trials in metastatic melanoma and renal cell carcinoma. Here, we provide an overview of the antitumour effects of IL21 and describe strategies to combine IL21 with other drugs for future cancer therapies.
dressNature Reviews Drug Discovery 04/2008; 7(3):231-40. · 29.01 Impact Factor
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ABSTRACT: Interleukin-21 (IL-21) is a cytokine with structural and sequence homology to IL-2 and IL-15, yet possesses several biological properties distinct from these cytokines. IL-21 is produced mainly by activated CD4(+) T cells and natural killer T cells and mediates its activity by binding to the IL-21 receptor (IL-21R), consisting of an IL-21-specific alpha chain (IL-21Ralpha; JAK/STAT) that heterodimerizes with the common gamma chain (CD132). Intracellular signaling occurs through the Janus-activated kinase/signal transducer and activator of transcription pathways. Physiologic expression of IL-21R is restricted to lymphoid tissues and peripheral blood mononuclear cells; however, other tissues such as epithelium, synovium, or transformed cells can acquire expression of both components of IL-21R heterodimer. IL-21 has complex activities on a wide variety of cell types, leading to enhancement of adaptive T-cell immunity, antibody production, activation of natural killer cell subtypes, and opposition to suppressive effects mediated by regulatory T cells. Functionally, these activities promote immune responses and point to a physiologic role of IL-21 in autoimmunity and immune enhancement. Therapeutic manipulation of IL-21 activity may allow improved immunotherapy for cancer as well as insights into autoimmune disease. Recently conducted phase 1 trials in metastatic melanoma and renal cell carcinoma have shown that recombinant IL-21 has a favorable safety profile and support its continued investigation as a potential anticancer drug.
Clinical Cancer Research 01/2008; 13(23):6926-32. · 7.74 Impact Factor
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ABSTRACT: Interleukin (IL)-21 is a recently discovered cytokine in early clinical development, which has shown anti-tumor activity in various animal models. In the present study, we examine the anti-tumor activity of IL-21 protein therapy in two syngeneic tumor models and its effect on the density of tumor infiltrating T cells. We treated mice bearing established subcutaneous B16 melanomas or RenCa renal cell carcinomas with intraperitoneal (i.p.) or subcutaneous (s.c.) IL-21 protein therapy and subsequently scored the densities of tumor infiltrating CD4(+) and CD8(+) T cells by immunohistochemistry. Whereas both routes of IL-21 administration significantly inhibited growth of small, established RenCa and B16 tumors, only s.c. therapy significantly inhibited the growth of large, established tumors. We found a greater bioavailability and significant drainage of IL-21 to regional lymph nodes following s.c. administration, which could account for the apparent increase in anti-tumor activity. Specific depletion of CD8(+) T cells with monoclonal antibodies completely abrogated the anti-tumor activity, whereas NK1.1(+) cell depletion did not affect tumor growth. In accordance, both routes of IL-21 administration significantly increased the density of tumor infiltrating CD8(+) T cells in both B16 and RenCa tumors; and in the RenCa model s.c. administration of IL-21 led to a significantly higher density of tumor infiltrating CD8(+) T cells compared to i.p. administration. The densities of CD4(+) T cells were unchanged following IL-21 treatments. Taken together, these data demonstrate that IL-21 protein has anti-tumor activity in established syngeneic tumors, and we show that IL-21 therapy markedly increases the density of tumor infiltrating CD8(+) T cells.
Cancer Immunology and Immunotherapy 10/2007; 56(9):1417-28. · 3.70 Impact Factor
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ABSTRACT: IL-21, a member of the common gamma-chain family of cytokines, has pleiotropic effects on T, B, and NK cells. We found that IL-21 and the prototype common gamma-chain cytokine IL-2 can stimulate proliferation and cytokine secretion by Ag-specific rhesus monkey CD8+ T cells. However, unique among the members of this family of cytokines, we found that IL-21 drives these cells to apoptosis by down-regulation of Bcl-2. These findings suggest that IL-21 may play an important role in the contraction of CD8+ T cell responses.
The Journal of Immunology 10/2007; 179(6):3596-603. · 5.79 Impact Factor
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Ian D Davis,
Birte K Skrumsager,
Jonathan Cebon,
Theo Nicholaou,
John W Barlow,
Niels Peter Hundahl Moller, Kresten Skak,
Dorthe Lundsgaard,
Klaus Stensgaard Frederiksen,
Peter Thygesen,
Grant A McArthur
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ABSTRACT: Human interleukin-21 (IL-21) is a pleiotropic class I cytokine that activates CD8(+) T cells and natural killer cells. We report a phase 1 study of recombinant human IL-21 in patients with surgically incurable metastatic melanoma. The primary objective was to investigate safety and tolerability by determining dose-limiting toxicity (DLT). The secondary objectives were to identify a dose response for various biomarkers in the peripheral blood, estimate the minimum biologically effective dose, determine the pharmacokinetics of IL-21, determine if anti-IL-21 antibodies were induced during therapy, and measure effects on tumor size according to Response Evaluation Criteria in Solid Tumors.
Open-label, two-arm, dose escalation trial of IL-21 administered by i.v. bolus injection at dose levels from 1 to 100 microg/kg using two parallel treatment regimens: thrice weekly for 6 weeks (3/wk) or three cycles of daily dosing for 5 days followed by 9 days of rest (5+9).
Twenty-nine patients entered the study. IL-21 was generally well tolerated and no DLTs were observed at the 1, 3, and 10 microg/kg dose levels. In the 3/wk regimen, DLTs were increased in alanine aminotransferase, neutropenia, and lightheadedness with fever and rigors. DLTs in the 5+9 regimen were increased in aspartate aminotransferase and alanine aminotransferase, neutropenia, fatigue, and thrombocytopenia. The maximum tolerated dose was declared to be 30 microg/kg for both regimens. Effects on biomarkers were observed at all dose levels, including increased levels of soluble CD25 and up-regulation of perforin and granzyme B mRNA in CD8(+) cells. One partial tumor response observed after treatment with IL-21 for 2 x 6 weeks (3/wk) became complete 3 months later.
IL-21 is biologically active at all dose levels administered and is generally well tolerated, and phase 2 studies have commenced using 30 microg/kg in the 5+9 regimen.
Clinical Cancer Research 07/2007; 13(12):3630-6. · 7.74 Impact Factor
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ABSTRACT: Type 1 diabetes (T1D) is an autoimmune disease in which the pancreatic beta-cells are destroyed in an immune-mediated process. In one mouse model of T1D, the co-expression of the costimulatory molecule, B7-1, and the pro-inflammatory cytokine, tumor necrosis factor (TNF)-alpha, on the beta-cells leads to massive insulitis and loss of beta-cells, resulting in T1D. Here, we have investigated whether the specific loss of beta-cells is due to an intrinsic defect in the beta-cells or is a direct consequence of B7-1 expression. We show that transgenic mice expressing TNF-alpha on the beta-cells and B7-1 on the alpha-cells are resistant to the development of diabetes despite B7-1-dependent loss of alpha-cells and a massive islet inflammation consisting of T cells, B cells, macrophages and dendritic cells. Furthermore, islets with alpha-cell expression of B7-1 develop alpha-cell destruction and heavy infiltration, but maintain functional beta-cells when they are engrafted into diabetic mice that co-express TNF-alpha and B7-1 on the beta-cells. Thus, our results show that the beta-cells are able to survive in a severely inflamed organ where the neighboring alpha-cells are destroyed, suggesting that in this model B7-1 expression on the target cells is the primary determinant for the loss of islet cells.
European Journal of Immunology 10/2005; 35(9):2583-90. · 5.10 Impact Factor
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ABSTRACT: The initial events leading to activation of the immune system in type 1 diabetes are still largely unknown. In vivo, dendritic cells (DCs) are thought to be the only antigen-presenting cells (APCs) capable of activating naïve T-cells and are therefore important for the initiation of the autoimmune response. To test the effect of activating islet-associated APCs in situ, we generated transgenic mice expressing CD154 (CD40 ligand) under control of the rat insulin promoter (RIP). RIP-CD154 mice developed both insulitis and diabetes, although with different incidence in independent lines. We show that activated DCs could be detected both in the pancreas and in the draining pancreatic lymph nodes. Furthermore, diabetes development was dependent on the presence of T- and B-cells since recombination-activating gene (RAG)-deficient RIP-CD154 mice did not develop diabetes. Finally, we show that the activation of immune cells was confined to the pancreas because transplantation of nontransgenic islets to diabetic recipients restored normoglycemia. Together, these data suggest that expression of CD154 on the beta-cells can lead to activation of islet-associated APCs that will travel to the lymph nodes and activate the immune system, leading to insulitis and diabetes.
Diabetes 11/2004; 53(10):2588-95. · 8.29 Impact Factor
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ABSTRACT: Treatment with ATP-sensitive K(+) channel openers (KCOs) leads to inhibition of insulin secretion and metabolic "rest" in beta-cells. It is hypothesized that in type 1 diabetes this may reduce beta-cell death resulting from metabolic stress as well as reduce the immunogenicity of the beta-cells during autoimmune beta-cell destruction. We have investigated whether the beta-cell-selective KCO compound, NN414, can be used to improve beta-cell survival in DR-BB rats rendered diabetic by modulation of their immune system. The rats were treated three times daily on days 1-19 with NN414, diazoxide, or vehicle. On day 21, an intravenous glucose tolerance test was conducted to assess beta-cell function. Postmortem histological analysis of rats' pancreata assessed the degree of insulitis and beta-cell volume. Among NN414-treated rats, 46% (16 of 35) were found to have a beta-cell mass similar to that of nondiabetic controls and significant glucose-stimulated C-peptide values, whereas only 11% (4 of 36) of vehicle-treated rats possessed a normal beta-cell mass and function (P < 0.002, by chi(2) test). Furthermore, responsive NN414-treated rats were almost free of insulitis. Thus, this study demonstrated that treatment with KCO compounds can indeed lead to preservation of beta-cell function and reduction of insulitis in a rat diabetes model.
Diabetes 04/2004; 53(4):1089-95. · 8.29 Impact Factor
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ABSTRACT: Maintenance of peripheral tolerance and inactivation of autoreactive T cells is based on a delicate balance between pro-inflammatory and protective cytokines that is poorly understood. We have here addressed how the local expression of the inflammatory cytokine TNF-alpha can impair peripheral tolerance and lead to autoreactivity. After transplantation of pancreata that are immunogenic due to beta-cell expression of B7.1 and TNF-alpha, into thymectomized and euthymic syngeneic mice, we found that only euthymic mice rejected the grafts. This result suggests that under normal circumstances autoreactive T cells are functionally inactivated, and initiation of an autoreactive response requires de-novo generation of T cells. By contrast, thymectomized mice expressing TNF-alpha on the endogenous islets rejected the grafts, showing that expression of TNF-alpha prevents functional silencing of the autoreactive T cells. Thus, this study provides a mechanism by which TNF-alpha and possibly chronic inflammatory responses may promote autoimmune diseases. Furthermore, we have investigated whether B7.1 can enhance T cell responses of already activated T cells leading to islet rejection. By transplantation of wild-type and B7.1-expressing islets into overtly diabetic mice we found that only the wild-type islets could restore normoglycemia, suggesting that costimulation by B7.1 is required in the expansion or effector phase of the response.
European Journal of Immunology 06/2003; 33(5):1341-50. · 5.10 Impact Factor
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ABSTRACT: Here we report that histone deacetylase inhibitors (HDAC-i) comprise a new class of immunosuppressive agents. HDAC-i inhibited CD4 T-cell proliferation in a dose-dependent manner, which was not caused by apoptosis or decreased viability. Although early intracellular signals such as tyrosine kinase activity and elevation of intracellular calcium concentration were not affected, the characteristic aggregation of T cells following activation was completely abrogated. This correlated with diminished activation-induced expression of the adhesion molecules. HDAC-i furthermore inhibited activation-induced CD25 and CD154 expression on CD4 cells, without affecting induction of CD69. HDAC-i inhibited CD154 expression by a mechanism distinctly different from cyclosporine-mediated inhibition. HDAC-i thus inhibited interleukin 2 (IL-2)-induced CD154 expression on effector T cells and constitutively expressed CD154 on various tumor cells, events that were not affected by cyclosporine. Additional studies showed that HDAC-i treatment inhibited c-Myc expression, which was further shown to be important for CD154 gene activation. These results demonstrate pronounced T-cell inhibitory activity of HDAC-i, which may form the basis of novel therapeutic interventions against autoimmune diseases and allograft rejection.
Blood 03/2003; 101(4):1430-8. · 9.90 Impact Factor
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ABSTRACT: Glucose responsiveness is a fundamental metabolic feature of pancreatic beta-cells. Glucose-regulated transcription of the insulin gene is in part mediated via the homeobox transcription factor PDX-1. Another islet protein and diabetes autoantigen, glutamic acid decarboxylase (GAD), has been shown to be subject to regulation by glycemia. We have studied the mRNA level of two isoforms of GAD, GAD(65) and GAD(67), and found that GAD(67) but not GAD(65) mRNA steady-state level is regulated by glucose. By transfection of a rat GAD(67) promoter-driven luciferase reporter gene into primary rat islet cells, we demonstrate glucose-regulated expression of the reporter gene. We show that PDX-1 is able to bind to two TAAT-boxes in the GAD(67) promoter and that functional disruption of these two PDX-1 binding elements has an additive effect in severely impairing glucose responsiveness of the GAD(67) promoter. These data strongly suggest that PDX-1 is involved in glucose-regulated expression of GAD(67).
Biochemical and Biophysical Research Communications 08/2002; 295(2):243-8. · 2.48 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: For decades cytokines such as type I interferons and IL-2 have been used in immunotherapy against cancer, viral hepatitis, and autoimmune diseases such as multiple sclerosis. However, the therapeutic use of cytokines has been hampered by their pleiotropic effects on target-cells. Thus, cytokines such as IFN-α and IL-2 have multiple and severe side effects. Accordingly, they are generally used at sub-optimal doses, which limit their clinical efficacy. Here we hypothesized that a combination of IFN-α and IL-21, a novel cytokine of the IL-2 family with anti-cancer effects, will increase the anti-cancer efficacy at sub-optimal cytokine doses. We show that the combined stimulation of target-cells with IFN-α and IL-21 triggers an increased STAT3 activation whereas the activation of other STATs including STAT1/2 is unaffected. In parallel, the combined stimulation with IFN-α and IL-21 triggers a selective increase in MHC class I expression and NK- and CD8+ T-cell-mediated cytotoxicity. In an experimental in vivo model of renal carcinoma, the combined treatment of IFN-α and IL-21 also produces a significant anti-cancer effect as judged by an inhibition of tumor growth and an increased survival. Taken together our data show that the combined use of IFN-α and IL-21 boosts STAT3 signaling, cytotoxicity, and anti-tumor efficacy, suggesting that a combinatorial therapeutic use of these cytokines may benefit cancer patients.
Molecular Immunology.
