Role of elastokines and impact of their carbamylation during vascular aging

Au cours du vieillissement vasculaire, l’accumulation progressive de modifications structurales et fonctionnelles au sein de la paroi vasculaire est associée au développement et à l’évolution des maladies cardiovasculaires (MCV). Parmi ces modifications, la fragmentation de l’élastine, générant la libération de peptides bioactifs (élastokines), et la carbamylation, modification post-traductionnelle non enzymatique altérant la structure et/ou les fonctions des protéines, sont reconnues comme des marqueurs précoces du vieillissement vasculaire et leur implication dans le développement de MCV a été démontré. Le but de ce travail de thèse était d’étudier l’effet des élastokines sur le processus de vieillissement vasculaire et d’analyser l’impact de la carbamylation sur ces effets. Les résultats, dans un modèle murin LDLR-/-, ont montré que les élastokines amplifient la fragmentation des fibres élastiques et favorisent la rigidité artérielle associées à une hypertension artérielle et une fatigue cardiaque. Ces résultats ont été complétés, in vitro, par la mise en évidence d’une modulation phénotypique importante des cellules musculaires lisses vasculaires sous l’effet des élastokines (augmentation de l’adhésion, diminution des capacités migratoires et de la rigidité cellulaire, stimulation des voies de signalisation et de l’expression de protéines contractiles). Parallèlement, la carbamylation des élastokines conduit généralement à l’inhibition de leurs effets biologiques. Ces résultats ouvrent de nouvelles voies de recherche quant à l’implication des élastokines dans le développement et la progression des MCV.During vascular aging, the progressive accumulation of structural and functional modifications within the vascular wall is associated with the development and progression of cardiovascular diseases (CVD). Among these modifications, elastin fragmentation, generating the release of bioactive elastin-derived peptides (elastokines), and carbamylation, a non-enzymatic post-translational modification altering protein structure and/or function, are recognized as early markers of vascular aging and have been shown to be involved in the development of CVD. The aim of this thesis was to study the effect of elastokines on the vascular aging process and to analyze the impact of carbamylation on these effects. The results in a LDLR-/- mouse model showed that elastokines amplify the fragmentation of elastic fibers and promote arterial stiffness in association with the development of arterial hypertension and cardiac fatigue. These results were completed, in vitro, by the demonstration of a significant phenotypic modulation of vascular smooth muscle cells mediated by elastokines (increase in adhesion, decrease in migratory capacities and cell stiffness, stimulation of signaling pathways and expression of contractile proteins). At the same time, carbamylation of elastokines generally leads to inhibition of their biological effects. These results open new pathways of research regarding the involvement of elastokines in the development and progression of CVD

Revealing the elasticity of an individual aortic fiber during ageing at nanoscale by in situ atomic force microscopy †

International audienceArterial stiffness is a complex process affecting the aortic tree that significantly contributes to cardiovascular diseases (systolic hypertension, coronary artery disease, heart failure or stroke). This process involves a large extracellular matrix remodeling mainly associated with elastin content decrease and collagen content increase. Additionally, various chemical modifications that accumulate with ageing have been shown to affect long-lived assemblies, such as elastic fibers, that could affect their elasticity. To precisely characterize the fiber changes and the evolution of its elasticity with ageing, high resolution and multimodal techniques are needed for precise insight into the behavior of a single fiber and its surrounding medium. In this study, the latest developments in atomic force microscopy and the related nanomechanical modes are used to investigate the evolution and in a near-physiological environment, the morphology and elasticity of aorta cross sections obtained from mice of different ages with an unprecedented resolution. In correlation with more classical approaches such as pulse wave velocity and fluorescence imaging, we demonstrate that the relative Young's moduli of elastic fibers, as well as those of the surrounding areas, significantly increase with ageing. This nanoscale characterization presents a new view on the stiffness process, showing that, besides the elastin and collagen content changes, elasticity is impaired at the molecular level, allowing a deeper understanding of the ageing process. Such nanomechanical AFM measurements of mouse tissue could easily be applied to studies of diseases in which elastic fibers suffer pathologies such as atherosclerosis and diabetes, where the precise quantification of fiber elasticity could better follow the fiber remodeling and predict plaque rupture. † Electronic supplementary information (ESI) available. Se