Interleukin 21 controls tumour growth and tumour immunosurveillance in colitis-associated tumorigenesis in mice

Background and aims: Colitis-associated tumorigenesis is a balance between proliferation of tumour cells and tumour immunosurveillance. The role of T-helper-cell-derived cytokines in tumour growth is not fully understood. In this study the authors investigated the influence of interleukin (IL) 21 on intestinal tumorigenesis. Methods: Chronic colitis was induced in IL-21−/− and littermate control wild-type mice with three cycles of 1.5% dextran sulphate sodium (DSS) over 7 days followed by 7 days of drinking water. Mice received an azoxymethane injection on day 0 of DSS-colitis to induce tumorigenesis. Immunohistochemistry was performed on inflamed and tumour-bearing areas of colons. Cytokine expression of isolated colonic CD4 T cells was determined by ELISA. Cytotoxic capacity of isolated colonic CD8 T cells targeting tumour cells was evaluated by flow cytometry and quantitative cytotoxicity assay. Apoptosis of tumour cells was determined by TUNEL assay of colonic sections. Results: Increasing expression of IL-21 was observed in chronic colitis, which showed functional importance, since IL-21 deficiency prevented chronic DSS-colitis development. Further, in the absence of IL-21, significantly fewer tumour nodules were detected, despite a similar extent of intestinal inflammation. In wild-type mice, 8.6±1.9 tumour nodules were found compared with 1.0±1.2 in IL-21-deficient mice. In tumour-bearing IL-21-deficient mice, intestinal inflammation was restored and partly dependent on interferon (IFN)-γ, whereas the inflammation in wild-type mice showed high IL-17A concentrations. In these rare tumours in IL-21-deficient mice, tumour cell proliferation (Ki-67) was decreased, while cell apoptosis was increased, compared with wild-type mice. Increased IFNγ expression in tumour-bearing IL-21-deficient mice led to increased tumour immunosurveillance mediated by cytotoxic CD8CD103 T cells targeting E-cadherin+ colonic tumour cells and therefore limited tumour growth. Conclusion: These results indicate that IL-21 orchestrates colitis-associated tumorigenesis, leading to the hypothesis that high IFNγ and low IL-17A expression reduces tumour cell proliferation and increases tumour immunosurveillance

TREM-1 als Zielstruktur zur Verlängerung des Transplantatüberlebens nach Herztransplantation

Eine der schwerwiegendsten Komplikationen nach solider Organtransplantation ist die gegen das Spenderorgan gerichtete Abstoßungsreaktion. Eine wichtige proinflammatorische Funktion des angeborenen Immunsystems, während der Toll-like Rezeptoren-abhängigen Immunantwort wird durch TREM-1 („triggering-receptor-expressed-on-myeloid-cells-1“) vermittelt. Ziel der Dissertation war es, die Beteiligung von TREM-1 während einer chronischen Abstoßungsreaktion bei Herztransplantaten in Mäusen zu untersuchen. Das Transplantationsmodell zeigte an Tag 7-10 einen beginnenden, progredienter Funktionsverlust des Transplantats mit einer vollständigen Abstoßung nach ca. 4 Wochen. Die zytometrische und immunhistologische Analysen von infiltrierenden Zellen zeigten eine dramatische Anreicherung von TREM-1+CD11b+MHC-II+F4/80+CCR2+ Antigen-Präsentierenden-Zellen und IFNγ-produzierende CD4+ T Lymphozyten im Transplantat während der Abstoßungsreaktion. Diese fehlten gänzlich nach einer syngenen Transplantation. Der positive Effekt einer Inhibition von TREM-1 auf die Transplantatfunktion im Verlauf einer chronischen Abstoßung, basierend auf einer verminderten Differenzierung von Th1 Zellen, dies führte zu der Hypothese, dass eine initiale Inhibierung des angeborenen Immunsystems ausreichend sein könnte um ein langfristiges Überleben der Transplantate zu gewährleisten. Experimente in der vorliegenden Doktorarbeit konnten tatsächlich bestätigen, dass sich bei Hemmung von TREM-1 in der initialen Phase der angeborenen Immunantwort das Langzeitüberleben der Herztransplantate deutlich verlängerte. Die Untersuchungen zur Fibrogenese nach Organtransplantation zeigten eine pathologische Kollagenablagerung im Gewebe mit nachfolgendem Funktionsverlust des Transplantats im Verlauf der chronischen Abstoßungsreaktion. IFNγ spielt in der Initialisierung des pro-fibrotischen Programms eine besondere Rolle. Es zeigte sich, dass eine Blockade von TREM-1 sich neben der verminderten Differenzierung von Th1 Zellen auch in einer reduzierten Fibrogenese manifestierte. Zusammenfassend sprechen die Ergebnisse dafür, dass der Ko-Rezeptor TREM-1 auf APC im Abstoßungsprozess immunregulatorisch auf die adaptive Immunantwort und die Fibrogenese, wie auch auf das Überleben der Transplantate wirkt. Diese Ergebnisse sind insbesondere von klinischer Relevanz, da TREM-1 bisher in Therapiestrategien des angeborenen Immunsystems zur Verlängerung des Transplantatüberlebens noch unzureichend untersucht wurde

IL-3 promotes the development of experimental autoimmune encephalitis

Little is known about the role of IL-3 in multiple sclerosis (MS) in humans and in experimental autoimmune encephalomyelitis (EAE). Using myelin oligodendrocyte glycoprotein (MOG) peptide-induced EAE, we show that CD4(+) T cells are the main source of IL-3 and that cerebral IL-3 expression correlates with the influx of T cells into the brain. Blockade of IL-3 with monoclonal antibodies, analysis of IL-3 deficient mice, and adoptive transfer of leukocytes demonstrate that IL-3 plays an important role for development of clinical symptoms of EAE, for migration of leukocytes into the brain, and for cerebral expression of adhesion molecules and chemokines. In contrast, injection of recombinant IL-3 exacerbates EAE symptoms and cerebral inflammation. In patients with relapsing-remitting MS (RRMS), IL-3 expression by T cells is markedly upregulated during episodes of relapse. Our data indicate that IL-3 plays an important role in EAE and may represent a new target for treatment of MS

IL-3 Triggers Chronic Rejection of Cardiac Allografts by Activation of Infiltrating Basophils

Chronic rejection is a major problem in transplantation medicine, largely resistant to therapy, and poorly understood. We have shown previously that basophil-derived IL-4 contributes to fibrosis and vasculopathy in a model of heart transplantation with depletion of CD4(+) T cells. However, it is unknown how basophils are activated in the allografts and whether they play a role when cyclosporin A (CsA) immunosuppression is applied. BALB/c donor hearts were heterotopically transplanted into fully MHC-mismatched C57BL/6 recipients and acute rejection was prevented by depletion of CD4(+) T cells or treatment with CsA. We found that IL-3 is significantly upregulated in chronically rejecting allografts and is the major activator of basophils in allografts. Using IL-3-deficient mice and depletion of basophils, we show that IL-3 contributes to allograft fibrosis and organ failure in a basophil-dependent manner. Also, in the model of chronic rejection involving CsA, IL-3 and basophils substantially contribute to organ remodeling, despite the almost complete suppression of IL-4 by CsA. In this study, basophil-derived IL-6 that is resistant to suppression by CsA, was largely responsible for allograft fibrosis and limited transplant survival. Our data show that IL-3 induces allograft fibrosis and chronic rejection of heart transplants, and exerts its profibrotic effects by activation of infiltrating basophils. Blockade of IL-3 or basophil-derived cytokines may provide new strategies to prevent or delay the development of chronic allograft rejection

Cellular Origin and Functional Relevance of Collagen I Production in the Kidney

Background Interstitial fibrosis is associated with chronic renal failure. In addition to fibroblasts, bone marrow-derived cells and tubular epithelial cells have the capacity to produce collagen. However, the amount of collagen produced by each of these cell types and the relevance of fibrosis to renal function are unclear. Methods We generated conditional cell type-specific collagen I knockout mice and used (reversible) unilateral ureteral obstruction and adenine-induced nephropathy to study renal fibrosis and function. Results In these mouse models, hematopoietic, bone marrow-derived cells contributed to 38%-50% of the overall deposition of collagen I in the kidney. The influence of fibrosis on renal function was dependent on the type of damage. In unilateral ureteral obstruction, collagen production by resident fibroblasts was essential to preserve renal function, whereas in the chronic model of adenine-induced nephropathy, collagen production was detrimental to renal function. Conclusions Our data show that hematopoietic cells are a major source of collagen and that antifibrotic therapies need to be carefully considered depending on the type of disease and the underlying cause of fibrosis

Deletion of Foxp3⁺ regulatory T cells in genetically targeted mice supports development of intestinal inflammation

<p>Abstract</p> <p>Background</p> <p>Mice lacking Foxp3⁺ regulatory T (Treg) cells develop severe tissue inflammation in lung, skin, and liver with premature death, whereas the intestine remains uninflamed. This study aims to demonstrate the importance of Foxp3⁺ Treg for the activation of T cells and the development of intestinal inflammation.</p> <p>Methods</p> <p>Foxp3-GFP-DTR (human diphtheria toxin receptor) C57BL/6 mice allow elimination of Foxp3⁺ Treg by treatment with Dx (diphtheria toxin). The influence of Foxp3⁺ Treg on intestinal inflammation was tested using the CD4⁺ T-cell transfer colitis model in Rag^−/− C57BL/6 mice and the acute DSS-colitis model.</p> <p>Results</p> <p>Continuous depletion of Foxp3⁺ Treg in Foxp3-GFP-DTR mice led to dramatic weight loss and death of mice by day 28. After 10 days of depletion of Foxp3⁺ Treg, isolated CD4⁺ T-cells were activated and produced extensive amounts of IFN-γ, IL-13, and IL-17A. Transfer of total CD4⁺ T-cells isolated from Foxp3-GFP-DTR mice did not result in any changes of intestinal homeostasis in Rag^−/− C57BL/6 mice. However, administration of DTx between days 14 and 18 after T-cell reconstitution, lead to elimination of Foxp3⁺ Treg and to immediate weight loss due to intestinal inflammation. This pro-inflammatory effect of Foxp3⁺ Treg depletion consecutively increased inflammatory cytokine production. Further, the depletion of Foxp3⁺ Treg from Foxp3-GFP-DTR mice increased the severity of acute dSS-colitis accompanied by 80% lethality of Treg-depleted mice. CD4⁺ effector T-cells from Foxp3⁺ Treg-depleted mice produced significantly more pro-inflammatory cytokines.</p> <p>Conclusion</p> <p>Intermittent depletion of Foxp3⁺ Treg aggravates intestinal inflammatory responses demonstrating the importance of Foxp3⁺ Treg for the balance at the mucosal surface of the intestine.</p