Supervisor: Dr Didier Communi
Targeting inflammation is now a recognized approach to reduce the risk of acute cardiovascular events. The main aim of the present project is to identify novel mechanisms of protection against myocardial infarction (MI), more specifically those involving anti- inflammatory proteins such as PD-L1 and adiponectin, and the release of cardioprotective exosomes. Exosomes represent a subtype of secreted vesicles that are now considered as a rising star in failing hearts by regulating cardiac function in health and disease. In contrast to stem cell-based therapies, exosomes display no apparent adverse effect based on their stability, biocompatibility, low toxicity and low immunogenicity. The study of the function and cargo of exosome subsets is crucial to understand the cellular crosstalk that initiate adaptative processes such as cardiac repair. It will also better define the future therapeutic use of anti- inflammatory exosomes in cardiovascular disease.
The mouse ischemia model used in our laboratory is the LAD (left artery descending artery) ligation model. Our laboratory has an expertise in the study of P2Y nucleotide receptors and their role in the cardiovascular field. Mouse P2Y4 is a G-protein-coupled receptor for UTP and ATP. We observed that mice deficient for P2Y4 nucleotide receptor (P2Y4 knockout (KO) mice) display smaller infarcts in the LAD ligation model, and an overexpression of the cardioprotective adipokine, adiponectin, compared with wild-type (WT) mice. We demonstrated the central role of PD-L1 (Programmed Death- ligand 1) and adiponectin in the cardioprotection resulting from P2Y4 receptor loss. Interestingly, protection against MI observed in P2Y4 KO mice was inhibited both by intraperitoneal injection of an anti-PD-L1 neutralizing antibody, or GW4869, an inhibitor of exosome release. These data provide a solid basis for this promising project related to the identification of cardioprotective exosomes.
Proposed PhD project
We will investigate if exosomal PD-L1, a major actor in tumor immunotherapy, is also an active player in cardioprotection. We will characterize the anti-inflammatory exosomes associated to PD-L1 and adiponectin overexpression in P2Y4 KO mice. The project aims to:
- evaluate the effect of exosome inhibitors injection on heart inflammation, fibrosis and function of P2Y4 KO ischemic mice (LAD ligation experiments).
- characterize the exosome subsets from plasma and adipocyte supernatants involved in adiponectin- and PD-L1-mediated cardioprotection in P2Y4 KO mice using flow cytometry, ExoView® platform, transmission electron microscopy and mass spectrometry; and analyze the exosome capacity to polarize leukocytes in vitro.
- identify the cardioprotective mechanisms identified in P2Y4 KO ischemic mice that are lost in P2Y4/adiponectin and P2Y4/PD-L1 double KO ischemic mice.
Moreover, we published recently a loss-of-function N178T polymorphism in P2RY4 human gene associated with reduced cardiac severity scores in patients with coronary artery disease. The present PhD project will thus also have a promising translational part with the study of PD-L1 level and exosome subsets in the plasma of patients having N178T mutation in P2RY4 gene. The study of receptors regulating cardiac inflammation might lead to their pre-clinical validation as new targets for MI treatment.
Scientific environment and available resources
The functioning costs associated to the project have already been granted by the FNRS, the Fonds pour la Chirurgie Cardiaque and the Belgian Heart Foundation. The PhD student will benefit from a collaboration with another PhD student using the same techniques and from the powerful infrastructure of IRIBHM including transgenesis, RNA-sequencing and proteomics platforms. We have a close collaboration with the Institut des Maladies Métaboliques et Cardiovasculaires (Toulouse, France) that gives us access to plasma and DNA samples from a cohort of 800 patients with coronary artery disease. Moreover, our laboratory is integrated in the BWG-BRC group (Belgian Working Group on Basic Research in Cardiology) within the Belgian Society of Cardiology (BSC). This interuniversity group allows multiple interactions beween students in cardiac laboratories during meetings, and gives us access to various expertises in heart failure, echocardiography and ischemia models, and to samples of human pathological hearts.