Abstract 228: Multi-omics Mapping Generates a Molecular Atlas of the Aortic Valve and Reveals Networks Driving Disease

Abstract

Background: No pharmacological therapy exists for calcific aortic valve disease (CAVD), which confers a dismal prognosis without valve replacement. The search for therapeutics and early diagnostics is challenging since CAVD presents in multiple pathological stages. Methods: A total of 25 human stenotic aortic valves obtained from valve replacement surgery were analyzed by multiple modalities, including transcriptomics and global unlabeled and tandem-mass-tagged proteomics by liquid chromatography-mass spectrometry. Results: Global transcriptional and protein expression signatures differed between the non-diseased, fibrotic, and calcific stages of CAVD, with consistent trends in gene and protein expression across disease stages. Anatomical aortic valve microlayers exhibited unique proteome profiles that were maintained throughout disease progression, and revealed GFAP as a specific marker of valvular interstitial cells (VICs) from the spongiosa layer. CAVD disease progression was marked by an emergence of smooth muscle cell activation, inflammation, and calcification-related pathways. Proteins overrepresented in the disease-prone fibrosa are functionally annotated to fibrosis and calcification pathways, and we found that, in vitro , fibrosa-derived VICs demonstrated greater calcification potential than those from the ventricularis. These studies confirmed that the microlayer-specific proteome was preserved in cultured VICs, and that VICs exposed to TNAP-dependent and TNAP-independent calcifying stimuli had distinct proteome profiles, both of which overlapped with that of the whole tissue. Network analysis of protein-protein interaction networks found a significant closeness to multiple inflammatory and fibrotic diseases. Conclusions: A spatially- and temporally-resolved multi-omics and systems biology strategy identifies the first molecular regulatory networks in CAVD, a cardiac condition without a pharmacological cure, and describes a strategy for endophenotype characterization that is broadly applicable to comprehensive omics studies of cardiovascular diseases.