ERC FUNDED PROJECTS

Systemic sclerosis (SSc) is an autoimmune disease that culminates in excessive extra-cellular matrix deposition (fibrosis) in skin and internal organs. SSc is a severe disease in which fibrotic events lead to organ failure such as renal failure, deterioration of lung function and development of pulmonary arterial hypertension (PAH). Together, these disease hallmarks culminate in profound disability and premature death. Over the past three years several crucial observations by my group changed the landscape of our thinking about the ethiopathogenesis of this disease. First, plasmacytoid dendritic (pDCs) cells were found to be extremely frequent in the circulation of SSc patients (1000-fold) compared with healthy individuals. In addition, we observed that pDCs from SSc patients are largely dedicated to synthesize CXCL4 that was proven to be directly implicated in fibroblast biology and endothelial cell activation, two events recapitulating SSc. Finally, research aimed to decipher the underlying cause of this increased pDCs frequency led to the observation that Runx3, a transcription factor that controls the differentiation of DC subsets, was almost not expressed in pDC of SSc patients. Together, these observations led me to pose the “SSc immune postulate” in which the pathogenesis of SSc is explained by a multi-step process in which Runx3 and CXCL4 play a central role. The project CIRCUMVENT is designed to provide proof of concept for the role of CXCL4 and RUNX3 in SSc. For this aim we will exploit a unique set of patient material (cell subsets, protein and DNA bank), various recently developed in vitro techniques (siRNA for pDCs, viral over expression of CXCL4/RUNX3) and apply three recently optimised experimental models (CXCL4 subcutaneous pump model, DC specific RUNX3 KO and the SCID/NOD/rag2 KO mice). The project CIRCUMVENT aims to proof the direct role for Runx3 and CXCL4 that could provide the final step towards the development of novel therapeutic targets

1 500 000 €

Start date: 2012-08-01, End date: 2017-07-31

"NK cells are innate lymphocytes that play a role in the early response against intracellular pathogens and against tumors. Several NK cell subsets have been described in peripheral organs that correspond to discrete stages of in vivo maturation. How NK cells differentiate from early precursors and what are the specific functions of each NK cell subset are unresolved issues. Here, we propose a three-aim program to address these questions. First, we want to revisit the partition of the NK cell population that is currently based on surface markers of undefined function by looking at the expression of transcription factors (TF) essential for NK cell development and maturation, such as T-bet and Eomes, using novel TF reporter mice. This strategy should also allow us to identify very early steps of NK cell development (NK cell progenitors) that remain ill defined. Second, we will try and identify molecular mechanisms that induce transition between NK cell maturation stages. For this we will take advantage of a previous gene profiling analysis that pointed at several pathways and TF that were highly regulated during NK cell maturation. The role of these pathways and TF in the differentiation of NK cells will be measured using a novel Cre/lox system allowing NK-specific gene deletion. Detailed analysis of mouse mutants will be used to delineate the role of selected genes and pathways in NK cell differentiation. Third, we will compare patterns of migration, cytokine secretion, in vivo cytotoxicity and global gene expression by individual NK cell subsets during an airway infection by Influenza to get insight on the specific functions of NK cell subsets during immune responses. Altogether, the results of this study should provide developmental, molecular and functional evidences to support the physiological relevance of NK cell subsets. This may improve strategies that aim at manipulating NK cell function for the benefit of patients with cancer or chronic infectious diseases"

1 340 757 €

Start date: 2012-01-01, End date: 2017-12-31

The endoplasmic reticulum (ER) serves many general functions, including the facilitation of protein folding and the transport of synthesized proteins, but it also has an important and more specialized role in sensing cellular stress. ER-stress identifies a group of signals that induce a transcriptional program enabling cells to survive protein overload and injury in the ER. This highly coordinated response involves three parallel signaling branches localized at the ER, namely IRE1, ATF6 and PERK. New findings suggest that these signaling pathways may regulate cellular processes independently of the ER-stress response. We have previously shown that some innate immune receptors such as Toll-like receptors specifically activate the IRE1 signaling pathway to enhance cytokine production. However, this is an emerging field of research and little is known on the specific nature of ER-signaling pathways and their function in regulating pathways in absence of a classical ER-stress response. The longterm goals of this proposal are to elucidate the molecular mechanisms and pathways emerging from the ER and regulating innate immune responses, and to address the physiological role of specific ER-signaling pathways in inflammation. Three complementary research sub-projects were designed. The first sub-project will identify and characterize compounds and conditions that trigger specific ER-signaling pathways. The second sub-project focuses on the biochemical characterization of signaling pathways emerging from the ER-associated kinases IRE1 and PERK. The third sub-project is aimed at investigating mechanisms by which ER-signaling pathways affect innate immune and inflammatory responses. The knowledge gained from this study will provide a better understanding of the mechanisms by which the ER and the cytosol interact to orchestrate physiological responses that help the organism to cope with infections and pathogenic insults.

1 498 076 €

Start date: 2012-01-01, End date: 2016-12-31

"Cell-cell synapses are an exquisitely evolved means of communication between cells. During the formation of the immune synapse (IS), diverse transmembrane and membrane associated molecules are reorganized into a highly segregated structure at the T cell–Antigen-Presenting Cell (APC) contact site. As part of this process, the tubulin cytoskeleton is vectorially directed toward the center of the IS, where the microtubule-organizing center (MTOC) localizes. MTOC translocation is an early event in IS formation that brings the secretory apparatus into close apposition with the APC, thus providing the basis for polarized secretion. The proposal aims to define how the MTOC controls cytoskeletal rearrangement and communication at the IS, as a mechanism for macromolecule transport and nucleation of signalling molecules during synaptic contact. We will study the mechanisms of MTOC-mediated polarization of multivesicular bodies (MVB) and exosome delivery during IS formation, and will assess the role in these processes of MTOC translocation regulators (HDAC6) and microtubule (MT) polymerization promoters (Plk1 and EB1). MTOC-dependent mitochondrial polarization to the IS will be assessed as a bioenergetic source for cytoskeletal rearrangements, IS maturation and polarized exosomal delivery. In particular, our proposed study of the possible horizontal transfer of miRNAs during cognate interactions between immune cells has the potential to reveal how miRNAs can control the early initiation of immunity. We will investigate the mechanism of directional transfer of RNA-harbouring exosomes at the IS from T cell to APC, and will examine the functional consequences of this transfer on APC biology and on the immune response. These studies will open avenues for the treatment of immune-related diseases."

2 011 200 €

Start date: 2012-02-01, End date: 2017-01-31