Pharmacotherapies for improving arterial structure-function in pathological conditions related to elastic fiber alterations

1/ Context:

Elastic fibers, made of 90% elastin, provide arteries with elasticity and allow for smoothing of the pulsatile blood pressure and flow ejected by the heart, therefore permitting normal hemodynamics and tissue perfusion^1-2. Elastic fibers are synthesized only until adolescence, by vascular smooth muscle cells (VSMCs) in arteries, then are progressively degraded due to the action of elastases and billions of mechanical arterial stretching-rest cycles, resulting in arterial function alteration^1-2. Several conditions, in patients and their mouse models, severely impact elastic fibers and arterial elasticity, including: i) the rare genetic disease Williams-Beuren syndrome (WBS), featuring aortic stenoses, arterial stiffening and hypertension, related to heterozygous deletion of the elastin gene (Eln^+/-)³, and ii) the non-genetic disease obstructive sleep apnea syndrome (OSAS, affecting up to 15-20% of the population), which main consequence is intermittent hypoxia (IH), which leads to hypertension, arterial stiffening, atherosclerosis and cardiac infarcts, with a medical cost of 1 billion €/year in France^4-7. There is presently no pharmaceutical treatment for patients. However, in murine models, different pharmacotherapies have been shown, by us and others, to improve arterial elastic fiber integrity and distensibility, unfortunately, for each of them, in different pathological contexts^8-11, hence not allowing for efficiency comparisons: i) potassium channel openers, such as minoxidil⁹, ii) an aqueous dill extract (DE)¹⁰, iii) a synthetic elastic protein (SEP) mimicking major structural and functional domains of tropoelastin, the elastin precursor (our ANR project Arterylastic, ANR-18-CE18-0001)¹¹.

2/ Objectives of the PhD thesis:

In order to identify the most efficient of these compounds, the beneficial effects of treatments with minoxidil, DE or SEP will be systematically compared in the exact same conditions, in both sexes, in the 2 animal models for conditions affecting the cardiovascular system, with damaged and no longer produced elastic fibers: Eln^+/- (for SVAS/WBS) or IH-exposed (for OSA) adult mice. This PhD work will be part of the recently accepted ANR project "Pharmacotherapies for improving Arterial STructure-function in pathological conditions related to Elastic fiber alterations" (PASTE, grant # ANR-25-CE52-0614 - committee Regenerative medicine).

In these animals, treated or not with one of our three compounds, parameters of aortic structure (dimensions, degradation of the wall, production and structural organization of elastic fibers) will be measured by 3D synchrotron X-ray tomography (task of laboratory MEDyC, Université Reims Champagne Ardenne, partner 2 of PASTE). The gene activations/inactivations (RNAseq) and different signaling pathways induced by the three compounds will be investigated in aortic VSMC cultures (task of laboratory LBTI, CNRS - Université Lyon 1, partner 3 of PASTE).

The corresponding physiological and mechanical parameters of the aorta and heart in the different animal groups will also be compared: blood pressure, microcirculatory blood flow, ejected blood flow, aortic and cardiac dimensions and compliance, dimensions and mechanics of the isolated aorta. This is the task our laboratory HP2 (Université Grenoble Alpes, partner 1 of PASTE), and a large part of it will be the purpose of the present proposal for a PhD position, together with collaborations with MEDyC and LBTI on their parts of the project.

Our ultimate translational goal is to propose the most efficient drug for clinical trials for arterial/cardiovascular improvement of WBS and OSAS/IH patients.

3/ Major parts of the PhD project:

- Supervision of the production of the mice and cells for the 3 PASTE partners,

- Production of primary cultures of vascular smooth muscle cells from mice

- In vivo measurement of the blood pressure in mice (tail-cuff sphygmomanometry and/or arterial catheterization),

- In vivo evaluation of blood flow in the microcirculation in mice (laser speckle contrast imaging),

- In vivo measurement of cardiac and aortic dimensions and functional parameters in mice (ultrasonography),

- Ex vivo measurement of heart weight and mechanics of the isolated aorta in mice (pressure arteriography).

The person who will be recruited will be trained to these different techniques.

It is expected that several articles will be published, some as leaders of the papers, some in collaborations with the other partners.

4/ Expected background of the candidates:

- Having good grades all along the university curriculum

- Curriculum in physiology (courses and practice), especially cardiovascular physiology.

- Experience of working with mice (or rats).

- Knowing and, better, mastering one, two or more cardiovascular physiology techniques

5/ Duration of employment and salary:

This PhD proposal corresponds to a 3-year position (from January 1st, 2026 until December 31st, 2028).

The monthly gross salary will be 2300 €.

Employer: Université Grenoble Alpes

7/ References:

1- Greenwald SE, Ageing of the conduit arteries, J. Pathol. 2007;211:157-172.

2- Fhayli W et al. Rise and fall of elastic fibers from development to aging. Consequences on arterial structure-function and therapeutical perspectives. Matrix Biol. 2019;84:41-56.

3- G. Faury et al. Developmental adaptation of the mouse cardiovascular system to elastin haploinsufficiency. J. Clin. Invest., 112:1419-1428, 2003.

4- Lévy P et al. Obstructive sleep apnoea syndrome. Nat Rev Dis Primers. 2015;1:15015.

5- Arnaud C et al. The Inflammatory Preatherosclerotic Remodeling Induced by Intermittent Hypoxia Is Attenuated by RANTES/CCL5 Inhibition. Am J Respir Critical Care Medicine 2011;184:724-731.

6- Wang J et al. Impact of Obstructive Sleep Apnea Syndrome on Endothelial Function, Arterial Stiffening, and Serum Inflammatory Markers: An Updated Meta-analysis and Metaregression of 18 Studies. J Am Heart Assoc. 2015;4:e002454.

7- Harki O et al. Inhibition of Vascular Endothelial Cadherin Cleavage Prevents Elastic Fiber Alterations and Atherosclerosis Induced by Intermittent Hypoxia in the Mouse Aorta. Int J Mol Sci. 2022;23:7012.

8- Ben Zemzem A et al. Early Alterations of Intra-Mural Elastic Lamellae Revealed by Synchrotron X-ray Micro-CT Exploration of Diabetic Aortas. Int J Mol Sci. 2022;23:3250.

9- Coquand-Gandit M et al. Chronic treatment with minoxidil induces elastic fiber neosynthesis and functional improvement in the aorta of aged mice. Rejuvenation Res. 2017;20:218-230.

10- Fhayli W et al. Dill Extract Induces Elastic Fiber Neosynthesis and Functional Improvement in the Ascending Aorta of Aged Mice with Reversal of Age-Dependent Cardiac Hypertrophy and Involvement of Lysyl Oxidase-Like-1. Biomolecules. 2020;10:173.

11- Boëté Q et al. Physiological impact of a synthetic elastic protein in arterial diseases related to alterations of elastic fibers: effect on the aorta of elastin-haploinsufficient male and female mice. Int J Mol Sci. 2022;23:13464.

Université Grenoble Alpes (UGA) is located in Grenoble (France), and has teaching and research activities in most fields (biology, mathematics, physics, chemistry, engineering, psychology, human sciences, literature, ...).

Laboratory HP2 focuses on the cardiovascular impact of OSA in clinics and IH-exposed animal models presenting cardiovascular features of OSA. HP2 masters a set of physiological, pharmacological and biochemical techniques, cellular and animal/preclinical models, and clinical research.

Supervision of the PhD thesis will be conducted by Pr. Gilles Faury, HP2 deputy director, full professor since 2004 at UGA. He specializes and is acknowledged in the study of cardiovascular, especially arterial, physiopathology related to genetic deficiency in elastic fiber components (elastin, fibrillin-1) or sleep apnea/intermittent hypoxia, during adulthood and aging. He is author of ~60 publications in international journals and participated to several European (TELASTAR-5th PCRD; ELASTAGE-6th PCRD) and national (ARTERYLASTIC, ANR-18-CE18-0001) research projects. He is the coordinator of the recently accepted ANR project PASTE (ANR-25-CE52-0614), in the context of which the present PhD thesis will be prepared.

- Having obtained a Master degree in biology

- Having good grades all along the university curriculum

- Curriculum in physiology (courses and practice), especially cardiovascular physiology.

- Experience of working with mice (or rats).

- Knowing and, better, mastering one, two or more cardiovascular physiology techniques