Clostridioides difficile, an anaerobic Gram-positive spore-forming bacterium, is responsible for a wide spectrum of infections ranging from diarrhea to life-threatening pseudomembranous colitis. The use of antibiotic therapy raises concerns about the selection of antibiotic-resistant bacteria at hospitals. New therapeutic targets should be investigated as alternatives to antibiotic treatments. Polysaccharides (PS) biosynthesis enzymes are encoded in a PS locus where most genes are essential for bacterial viability. We propose therefore the enzymes involved in PS biosynthesis as new therapeutic targets. Moreover, vaccines currently under development target the toxins and may not prevent C. difficile colonization and dissemination. We also propose in this project to evaluate PSII and/or LTA as vaccine component(s) of a vaccine that may prevent C. difficile colonization and dissemination. To that aim, the project will (i) define if either one or both PSII and LTA are essential for bacterial viability, ii) identify specific enzymes involved in PSII or LTA biosynthesis, (iii) target them with inhibitors and (iv) test PSII and LTA as vaccine candidates using an innovative approach. We recently developed a new genetic conditional lethal mutant system and have already obtained antibodies directed against PSII. Using these tools, we showed that the PSII seems to be essential for bacterial viability. The project will be divided into three tasks. The first will determine whether PSII, its anchoring and/or LTA are essential and define at least two enzymes as new therapeutic targets, one of each involved in each PS biosynthesis. The second task will look for inhibitors able to target these specific enzymes, using in silico models and a chemistry approach. The last task will test PSII and LTA as vaccine candidates. This project aims to combat C. difficile infections and prevent them using vaccination.

Despite decades of lipid lowering drug delivery, prevention strategies and efforts in research, cardiovascular diseases, mainly caused by atherosclerosis, are still the leading cause of death worldwide. New therapies are then mandatory to reduce the residual cardiovascular risk and to prevent atherothrombotic events. Atherosclerosis is a chronic inflammatory disease of the vascular wall triggered by low density lipoprotein internalisation within the subendothelial space. More than the obstruction of the arterial lumen, instability and rupture of the plaque are now recognized as the most deleterious events. Among processes triggering plaque instability, intraplaque neovascularization accelerates plaque progression, induces plaque rupture and attenuates statin benefit in human. Our preliminary data identified the nuclear receptor Rev-erb-a as a putative inhibitor of intraplaque neovascularization in human and mouse plaques in vivo as well as in vitro in endothelial cells. We then hypothesize that Rev-erb-a represents a new anti-atherogenic target that prevents intraplaque neovascularization by inhibiting the angiogenic activity of endothelial cells. This proposal will be the first to address the role of Rev-erba in angiogenesis and intraplaque neovascularization. This project will involve original available mouse models, innovative validated whole organ imaging techniques, in combination with cellular omics and mechanistic studies and a translational clinical part addressing the relevance of experimental results to human disease. We anticipate to identify Rev-erb-a as a novel therapeutic target to reduce intraplaque neovascularization and cardiovascular diseases.

Dendritic cells (DC) are crucial players in the initiation of adaptive immune response. A key feature of DC is their high capacity to capture antigens in peripheral tissues and migrate to draining lymph nodes (LN). In psoriasis, migratory IL-23-secreting DC drive T cell activation in LN and IL-17 release. Metabolism controls key DC functions but metabolic pathways governing migratory processes and IL-23 secretion remain underexplored. This translational project between clinical and basic research teams aims to decipher how metabolic components affect DC migration and IL-23 production, trigger psoriasis and colitis and contribute to their exacerbation in metabolic disorders. We will use pre-clinical models, pharmacological inhibitors and human samples to a) define the metabolic demands of IL-23 producing DC; b) investigate metabolic rewiring of DC during psoriasis and colitis exacerbation by High Fat Diet c) investigate the role of glucose metabolism in DC migration in human psoriasis

Given the paucity of effective treatments for idiopathic pulmonary fibrosis (IPF), efforts should be made to test and to better characterize new anti-fibrotic drug candidates. The recent development of RNA-targeted therapies using chemically modified oligonucleotide (ASOs) therapeutics show promising clinical outcomes in the treatment of several diseases. This approach is relevant for undruggable targets including non-coding RNAs. Our recent data have highlighted the importance of a family of ncRNAs as key specific regulators of the TGF-? pathway and myofibroblast (MYFs) activation during the pathogenesis of fibroproliferative disorders including IPF. Targeting these ncRNAs using ASO-based therapeutics appears as an attractive therapeutic option and preclinical studies have shown encouraging data. However, these approaches need further developments for translation to the clinic. Our main objective is to optimize the delivery of therapeutic ASOs and address their specificity in mice models of lung fibrosis. Non-invasive imaging will provide unique data on the biodistribution of ASO, as well as on the peak of therapeutic efficacy. Single-cell pharmacogenomics approaches will then be used to evaluate the efficacy and specificity of our drug candidates, providing more specific insights into their mechanism of action and off-target effects in the different cell populations of the fibrotic lung. Finally, as a first proof-of-concept to validate this ASO-based drug in a human context, the best ASO formulation will be evaluated in IPF-derived primary lung fibroblasts using various approaches including single-cell transcriptomics to capture the effect of the drug on the plasticity of these mesenchymal cells. Our project will improve the current knowledge on ASO delivery and safety but should also decipher ncRNA-associated regulatory circuits during MYF differentiation / de-differentiation and their potential interactions with developmental pathways (?-catenin, TGF-? / SMAD, FGFs) reactivated in IPF.

Non-alcoholic fatty liver disease (NAFLD) is a major global health problem for which there are no effective treatments. Early stages of NAFLD are described by isolated hepatic lipid accumulation, which, over time, can lead to inflammation and fibrosis, called Non-alcoholic steatohepatitis (NASH). NAFLD and especially NASH are closely associated to dysfunction in hepatic glucose and lipid homeostasis. However, the mechanisms driving activation of the hepatic immune system and progression from steatosis to NASH, remain poorly understood. We recently identified hepatic dendritic cells (DC) as a key immune population that is associated with NASH in humans. We hypothesize that the altered metabolic environment, including excess circulating lipids, alters the hepatic DC population triggering progression to NASH. The present proposal aims to dissect the key intracellular metabolic pathways of hepatic DC that are affected by activation during NASH pathogenesis.