The scientific activity of team 2, in the last four years was focused on translational research. Our objectives are to understand the mechanisms of tissue degenerative diseases in human cardiovascular (CV) system, integrating both molecular, cellular and matrix dysfunctions in the CV tissue dys-homeostasis, and to develop preclinical and clinical diagnostic and therapeutic applications. We focused exploration on CV tissue remodeling on the role of proteases and on their consequences on cell and matrix.

We developed the concept of anoikis (adherent cell apoptosis provoked by cell detachment) applied to vascular pathology. In particular we demonstrated that serine proteases were capable to provoke smooth muscle cell detachment and death. We demonstrated this point with leukocyte elastase and with high concentration of thrombin. More relevantly, we demonstrated that the plasminogen activated in presence of smooth muscle cells, which expressed t-PA (or u-PA for other cells: endothelial cells, epithelial cells, fibroblasts). Then active plasmin injured adhesive glycoproteins, such as fibronectin, and provoked cell detachment and death. Our hypothesis is that anoikis is probably the main determinant of cell loss associated with CV tissue degenerative disease. The second concept that we developed is that parietal thrombi, including mural thrombus in AAA and dissections, intraplaque hemorrhages in atherothrombosis, septic thrombus in endocarditic vegetations, mural thrombus in atrial dysfunctions, are conveyor of proteases towards the vascular wall.

We demonstrated that the mural thrombus was is a driving force in the evolution of AAA by convecting blood-borne serine protease towards the arterial wall, including proteases of the fibrinolytic system and proteases contained in PolyMorphoNuclear leukocytes (PMNs). These centrifugal biological activities convected by the mural thrombus were linked to permanent luminal renewal of the thrombus dependent to on platelet activation. This luminal platelet-dependent renewal of the thrombus is a new target for functional imaging and new therapeutic development.

In aneurysm of the ascending aorta, we participate participated to the demonstration that mutation of the myosin (MYH-11) rod was involved in genetic form of TAA. We are exploring the role of areas of mucoid degeneration as a specific site for MMP-7 & -3 retention within the aortic wall. We also explore the involvement of the fibrinolytic system in the disappearance of SMC, and of platelet activation due to rheological disturbance, and its link to thrombin retention in areas of mucoid degeneration.

In atherothrombotic lesions (carotid endarterectomy samples), we demonstrated by differential proteomic the disappearance of HSP 27 and 70 secreted by smooth muscle cells, and degraded by proteases present in the core of the lesion: plasmin for HSP 27 and elastase for HSP 70. We demonstrated that plasmin generation is involved in human plaque vulnerability. We are now showing that proteases convected by polymorphonuclear leukocytes, mainly elastase and cathepsin G, are involved in plaque vulnerability and linked to intraplaque hemorrhages. These data lead us to propose the concept of blood-borne proteases convected by intraplaque hemorrhages, and activated and retained within the core by thrombus formation and PMN release.

In parallel, the mechanisms of elastin synthesis, and degradation, and their genetic determinants, were explored through experimental genetic approach in rats. Similarly, the profile of gene expression and protein release by the hypertensive arterial wall was explored in two strains of rats, differentially susceptible to L-NAME administration.

The studies on the mechanism of chronic rejection in allograft were also pursued in collaboration with the team of Antonino Nicoletti. We demonstrated that lymphoid neogenesis, developed in the adventitia in close contact of the allo-rejected vascular wall, was involved in the maturation of the immune response, including the development of the humoral response, specific of graft chronic rejection. These different approaches of chronic rejection, AAA, atheroma and hypertension allowed us to propose a new concept of vascular wall topological response to different injuries.

Studies on the role of calcium metabolism, within the cardiomyocyte in congestive heart failure and arrhythmias were also pursued through experimental approach of gene transfert in vivo and in transgenesis models in rats and now in mice. Therapeutic interests and limitations of If channel inhibitor has been explored in the model of aortic clipping in rats.

Our studies on lipid signaling concern the eicosanoids (prostanoids, leukotrienes...) in the human vascular wall in physiological and pathophysiological conditions. The eicosanoids, and in particular the cyclooxygenase pathway are investigated in the control of the vascular tone using a pharmacological approach. The roles of the 8 different prostanoid receptor subtypes (DP, EP1-4, FP, IP, TP) activated by prostaglandins and/or thromboxane and the enzymatic activities ( COX-1, COX-2, mPGES...) are examined. (http://vascular.free.fr/).

These different activities were supported by grants including from the European Union (Elast-Age; EuGene Heart), Inserm (Recurrent budget; Clinical Research Network on AAA), Ministery of Research (Cardiovascular Research National Agency) , Fundations (French Society of Cardiology; FRM; Fondation de France; Leducq Fundation), and Industrial partners (Guerbet; Servier; Biorad; Sanofi-Synthélabo; Danone; Pharmaleads).