High-throughput in vitro modelization of non-atherosclerotic arterial diseases – ModernArt

Spontaneous coronary artery dissection (SCAD) is an acute cardiac event, mostly affecting young, otherwise healthy, women, which can recur with potential deathly consequences. Up to 50% of SCAD patient present lesions of fibromuscular dysplasia (FMD) in other arteries, supporting a clinical link between these non-atherosclerotic arterial diseases, which predominantly affect women. No specific therapeutic approach or treatment is known to prevent occurrence or recurrence of SCAD events.

We recently coordinated genome-wide association study (GWAS) meta-analyses of FMD and SCAD, leading to the identification of 18 genetic risk loci for these diseases (4 for FMD, 17 for SCAD, 3 shared). Identified genetic risk loci involved non-coding variants located in regulatory elements active specifically in vascular smooth muscle cells (SMCs) and fibroblasts. We identified a strong genetic overlap between SCAD, FMD and other vascular diseases, suggesting that common pathological processes are involved. ModernArt project aims at integrating the information from genetic studies through a high-throughput in vitro analysis of SCAD/FMD associated genetic risk loci. It will take advantage of the central role of vascular SMCs in the genetic predisposition to SCAD/FMD, and of the recent development of CRISPR-based systems allowing scalable functional genomic approaches. This project will articulate around three main objectives.

First, we will establish potential links between SCAD, FMD and sex hormone signaling. Indeed, SCAD and FMD affect predominantly (80-90%) women before the age of menopause, and SCAD events were suggested to associate with brutal hormonal variations. However, no direct link with female hormones was established so far. We will use high-throughput genomic approaches to characterize transcriptomic targets of the nuclear receptors to estrogen, progesterone and androgens and to determine their binding sites into the genome. We will thus define the links of sex hormone receptors to SCAD/FMD-associated regulatory elements and genes.

In our second objective, we will try to unambiguously identify target genes at SCAD/FMD genetic risk loci. This is a key step to integrate the information from GWAS into potential indications about the pathophysiological mechanisms and new therapeutic approaches. To tackle this issue, we will conduct a high-throughput functional exploration of SCAD/FMD genetic risk loci using CRISPR-based enhancer perturbation associated to single-cell RNA-sequencing.

Third, we will aim at understanding the role of four SCAD/FMD loci in vascular physiopathology. Indeed, these loci are associated not only to SCAD and FMD, but to multiple vascular diseases including hypertension, migraine, coronary artery disease and several forms of arterial dissection and aneurysm. My hypothesis is that the target genes at these loci could have a central position in the gene regulatory network involved in non-atherosclerotic vascular diseases. We will use the CRISPR activation and inhibition systems developed throughout our project to characterize the regulatory and phenotypic consequences of activation/inhibition of these genes in vascular SMCs.

Altogether, the integration of regulatory information upstream and downstream of SCAD/FMD genetic risk loci could allow the prioritization of key targets in the development of new therapeutic approaches. Beyond SCAD and FMD, the methods and datasets obtained throughout this project will be applicable to several complex vascular diseases. In particular, this project will provide leads to understand and better manage the sex differences in the susceptibility to cardiovascular diseases.