ERC FUNDED PROJECTS

The Aryl hydrocarbon receptor is an evolutionary conserved widely expressed transcription factor that mediates the toxicity of a substantial variety of exogenous toxins, but is also stimulated by endogenous physiological ligands. While it is known that this receptor mediates the toxicity of dioxin, this is unlikely to be its physiological function. We have recently identified selective expression of AhR in the Th17 subset of effector CD4 T cells. Ligation of AhR by a candidate endogenous ligand (FICZ) which is a UV metabolite of tryptophan causes expansion of Th17 cells and the induction of IL-22 production. As a consequence, AhR ligation will exacerbate autoimmune diseases such as experimental autoimmune encephalomyelitis. Little is known so far about the impact of AhR ligands on IL-17/IL-22 mediated immune defense functions. IL-22 is considered a pro-inflammatory Th17 cytokine, which is involved in the etiology of psoriasis, but it has also been shown to be a survival factor for epithelial cells. AhR is polymorphic and defined as high or low affinity receptor for dioxin leading to the classification of high and low responder mouse strains based on defined mutations. In humans similar polymorphisms exist and although on the whole human AhR is thought to be of low affinity in humans, there are identified mutations that confer high responder status. No correlations have been made with Th17 mediated immune responses in mice and humans. This study aims to investigate the role of AhR ligands and polymorphisms in autoimmunity as well as protective immune responses using both mouse models and human samples from normal controls as well as psoriasis patients.

1 242 352 €

Start date: 2009-02-01, End date: 2014-01-31

"Humans are equipped with a variety of intrinsic immunity or host restriction factors. These evolved under positive selection pressure for diversification and represent a first line of defence against invading viruses. Unfortunately, however, many pathogens have evolved effective antagonists against our defences. For example, the capability of HIV-1 to counteract human restriction factors that interfere with reverse transcription, uncoating and virion release has been a prerequisite for the global spread of AIDS. We are just beginning to understand the diversity and induction of antiretroviral factors and how pandemic HIV-1 group M (major) strains evolved to counteract all of them. Here, I propose to use a genetics, proteomics and evolutionary approach to discover and define as-yet-unknown antiviral effectors and their inducers. To identify novel antiviral factors, we will examine the capability of all primate genes that are under strong positive selection pressure to inhibit HIV and its simian (SIV) precursors. This examination from the evolutionary perspective of the invading pathogen will also reveal which adaptations allowed HIV-1 to cause the AIDS pandemic. Furthermore, complex peptide-protein libraries representing essentially the entire human peptidome, will be utilized to identify novel specific inducers of antiviral restriction factors. My ultimate aim is to unravel the network of inducers and effectors of antiviral immunity - the ""Anti-Virome"" - and to use this knowledge to develop novel effective preventive and therapeutic approaches based on the induction of combinations of antiviral factors targeting different steps of the viral life cycle. The results of this innovative and interdisciplinary program will provide fundamental new insights into intrinsic immunity and may offer alternatives to conventional vaccine and therapeutic approaches because most restriction factors have broad antiviral activity and are thus effective against various pathogens."

1 915 200 €

Start date: 2013-04-01, End date: 2018-03-31

Spontaneous protein crystallization is a rare event in biology. Eosinophilic inflammation such as seen in the airways in asthma, chronic rhinosinusitis and helminth infection is however accompanied by accumulation of large amounts of extracellular Charcot-Leyden crystals. These are made of Galectin-10, a protein of unknown function produced by eosinophils, hallmark cells of type 2 immunity. In mice, eosinophilic inflammation is also accompanied by protein crystal build up, composed of the chitinase-like proteins Ym1 and Ym2, produced by alternatively activated macrophages. Here we challenge the current view that these crystals are just markers of eosinophil demise or macrophages activation. We hypothesize that protein crystallization serves an active role in immunoregulation of type 2 immunity. On the one hand, crystallization might turn a harmless protein into a danger signal. On the other hand, crystallization might sequester and eliminate the physiological function of soluble Galectin-10 and Ym1, or prolong it via slow release elution. For full understanding, we therefore need to understand the function of the proteins in a soluble and crystalline state. Our program at the frontline of immunology, molecular structural biology and clinical science combines innovative tool creation and integrative research to investigate the structure, function, and physiology of galectin-10 and related protein crystals. We chose to study asthma as the crystallizing proteins are abundantly present in human and murine disease. There is still a large medical need for novel therapies that could benefit patients with chronic steroid-resistant disease, and are alternatives to eosinophil-depleting antibodies whose long term effects are unknown.

2 499 846 €

Start date: 2018-08-01, End date: 2023-07-31

The goal of this project is to understand the mechanism of how highly disease specific autoantibodies are generated in response to the exposure to a foreign antigen. IgA autoantibodies reactive with the enzyme transglutaminase 2 (TG2) are typical of coeliac disease (CD). These antibodies are only present in subjects who are HLA-DQ2 or -DQ8, and their production is dependent on dietary gluten exposure. This suggests that CD4+ gluten reactive T cells, which are found in CD patients and which recognise gluten peptides deamidated by TG2 in context of DQ2 or DQ8, are implicated in the generation of these autoantibodies. Many small intestinal IgA+ plasma cells express membrane Ig hence allowing isolation of antigen specific cells. Whereas control subjects lack anti-TG2 IgA+ plasma cells, on average 10% of the plasma cells of CD patients are specific for TG2. We have sorted single TG2 reactive IgA+ plasma cells, cloned their VH and VL genes and expressed recombinant mAbs. So far we have expressed 26 TG2 specific mAbs. There is a strong bias for VH5-51 usage, and surprisingly the antibodies are modestly mutated. TG2 acts on specific glutamine residues and can either crosslink these to other proteins (transamidation) or hydrolyse the glutamine to a glutamate (deamidation). None of the 18 mAbs tested affected either transamidation or deamidation leading us to hypothesise that retained crosslinking ability of TG2 when bound to membrane Ig of B cells is an integral part of the anti-TG2 response. Four models of how activation of TG2 specific B cells is facilitated by TG2 crosslinking and the help of gluten reactive CD4 T cells are proposed. These four models will be extensively tested including doing in vivo assays with a newly generated transgenic anti-TG2 immunoglobulin knock-in mouse model.

2 291 045 €

Start date: 2011-05-01, End date: 2017-04-30