Abstract Body (Do not enter title and authors here): Background: Acute Type A dissection (ATAD) incurs 15-30% mortality risk despite emergency surgery. There is an urgent need for precision medicine prognosticative tools to indicate prophylactic surgery (beyond diameter criteria). Although aortic bioinformatic studies have been performed, relatively few have investigated non-extracellular matrix (ECM) pathways. Whole genome sequencing (WGS) analyses, the impact of post-translational modifications (PTMs), are unexplored, as are the correlation of biomarkers with functional parameters of aortic disease beyond diameter alone.

Objective: To perform comprehensive, high-throughput, multiomic, clinical, and functional analyses on 816 human aortic tissue and plasma samples. To identify and validate novel non-ECM pathways of ATAD risk and confirm functional consequences of pathway alterations in vitro.

Methods: 816 samples from 232 individuals with elective aneurysm, ATAD, and control (transplant donors) were collected. Deep multiomic profiling entailed: WGS, proteomics, phosphoproteomics, ubiquitomics, acetylomics, and aortic tissue biomechanics. Follow up validation experiments were also performed.

Results: Across all samples, 6478 proteins, 1538 phosphosites, 529 acetylation, and 364 ubiquitination sites were quantified, as were 1360 rare genetic variants. Significant alterations in cytoskeletal regulatory proteins were observed across all omics levels based on disease state and importantly correlated with worsening aortic biomechanics (Fig 1A-C). Key biomarkers, including CTTNS418, were validated by immunofluorescence (1B). Multiomic integration showed distinct phenotypic clusters, driven by (phospho)proteomic features (Fig 2). In vitro, CTTNS418 altered cellular adhesion and contractility in human primary VSMCs, which may explain pathophysiologic progression of aneurysm to ATAD-risk state (Fig 3A). Novel nanoparticle-enrichment plasma proteomics distinguished aneurysm and ATAD phenotypes; significant differences in cytoskeletal regulatory pathways mirrored findings at the tissue-level (Fig 3B).

Conclusions: Multiomic profiling of >800 human samples revealed significant cytoskeletal regulatory pathway changes and provided first evidence that PTMs play a role in aortopathy pathogenesis. Key biomarkers importantly correlated with aortic functional parameters (beyond diameter), lead to phenotypic consequences in VSMC function, and pathways were concordantly altered in plasma, showing promise for clinical application.