Plasma proteins and onset of atherosclerosis: integrating human plasma proteogenomics, transcriptomics and in vivo evidence

Atherosclerosis, a progressive inflammatory disease and the leading cause of cardiovascular disease (CVD), remains a global health burden due to the lack of effective early therapeutic interventions. Although growing evidence highlights the involvement of plasma proteins in atherogenesis, their causal contributions to disease pathogenesis are poorly understood. To address this gap, we conducted a proteome-wide Mendelian randomization (MR) analysis using cis-pQTLs (cis-protein quantitative trait loci) from the deCODE and UKB-PPP cohorts (~90,000 individuals) as instrumental variables. We integrated colocalization analysis, summary-data-based MR (SMR), and HEIDI tests to systematically prioritize causal plasma proteins. Key findings were replicated in the CARDIOGRAMplusC4D (coronary artery disease, CAD) and FinnGen (CVD) cohorts. Functional validation was performed through phenome-wide association studies (PheWAS), single-cell transcriptomics, histological staining, and ELISA assays to characterize protein expression patterns in specific cell types and tissues. Among 2,711 plasma proteins analyzed, 28 showed strong genetic associations with atherosclerosis. Of these, five proteins (ADK, ANGPTL4, CD4, MGAT1, SYT11) met strict validation criteria through colocalization (posterior probability of colocalization, PP.H4 > 0.8) and SMR. Subsequent replication using MR and PheWAS further confirmed the causal roles of ADK, CALB2, and COMT in CAD and other CVD outcomes. Notably, CALB2 was specifically enriched in mast cells within atherosclerotic plaques and adipose tissue, and plasma levels were significantly elevated in patients with severe carotid artery stenosis (CAS). This study identifies 28 novel therapeutic targets for atherosclerosis using a rigorous multi-omics approach. Our findings establish CALB2 as a promising biomarker and therapeutic target, particularly in severe CAS, by linking genetic evidence to cell-type-specific expression and clinical phenotypes. These insights pave the way for precision medicine approaches in the prevention and treatment of CVD.