Objective: To determine whether MCP-1 (monocyte chemoattractant protein 1) levels in human atherosclerotic plaques associate with plaque vulnerability features. Approach and Results: We measured MCP-1 levels in human atherosclerotic plaque samples from 1199 patients in the Athero-EXPRESS Biobank who underwent endarterectomy for treatment of carotid stenosis. We explored associations with histopathologic and molecular features of plaque vulnerability, clinical plaque manifestations, and vascular events up to 3 years after endarterectomy. Following adjustments for age, sex, and vascular risk factors, MCP-1 plaque levels were associated with histopathologic markers of plaque vulnerability (large lipid core, low collagen content, high macrophage burden, low smooth muscle cell burden, intraplaque hemorrhage) and with a composite vulnerability index (range 0–5, β per SD increment in MCP-1, 0.42 [95% CI, 0.30–0.53], P =5.4×10 −13 ). We further found significant associations with higher plaque levels of other chemokines and proinflammatory molecules and markers of neovascularization and matrix turnover. When exploring clinical plaque instability, MCP-1 plaque levels were higher among individuals with symptomatic plaques as compared with those with asymptomatic plaques (odds ratio per SD increment in MCP-1, 1.36 [95% CI, 1.09–1.69]). MCP-1 levels were further associated with a higher risk of periprocedural major adverse vascular events and strokes occurring in the first 30 days after plaque removal. Conclusions: Higher MCP-1 plaque levels are associated with histopathologic, molecular, and clinical hallmarks of plaque vulnerability in individuals undergoing carotid endarterectomy. Our findings highlight a role of MCP-1 in clinical plaque instability in humans and complement previous epidemiological, genetic, and experimental studies supporting the translational perspective of targeting MCP-1 signaling in atherosclerosis.

Aim GWASs have discovered hundreds of common genetic variants for atherosclerotic disease and cardiovascular risk factors. The translation of susceptibility loci into biological mechanisms and targets for drug discovery remains challenging. Intersecting genetic and gene expression data has led to the identification of candidate genes. However, previously studied tissues are often non-diseased and heterogeneous in cell composition, hindering accurate candidate prioritization. Therefore, we analyzed single-cell transcriptomics from atherosclerotic plaques for cell-type-specific expression to identify atherosclerosis-associated candidate gene-cell pairs. Methods and Results We applied gene-based analyses using GWAS summary statistics from 46 atherosclerotic and cardiovascular disease, risk factors, and other traits. We then intersected these candidates with scRNA-seq data to identify genes specific for individual cell (sub)populations in atherosclerotic plaques. The coronary artery disease loci demonstrated a prominent signal in plaque smooth muscle cells (SKI, KANK2, SORT1) p-adj. = 0.0012, and endothelial cells (SLC44A1, ATP2B1) p-adj. = 0.0011. Finally, we used liver-derived scRNA-seq data and showed hepatocyte-specific enrichment of genes involved in serum lipid levels. Conclusion We discovered novel and known gene-cell pairs pointing to new biological mechanisms of atherosclerotic disease. We highlight that loci associated with coronary artery disease reveal prominent association levels in mainly plaque smooth muscle cell and endothelial cell populations. We present an intuitive single-cell transcriptomics-driven workflow rooted in human large-scale genetic studies to identify putative candidate genes and affected cells associated with cardiovascular traits. Collectively, our workflow allows for the identification of cell-specific targets relevant for atherosclerosis and can be universally applied to other complex genetic diseases and traits. Translational perspective GWAS identified a large number of genomic loci associated with atherosclerotic disease. The translation of these results into drug development and faster diagnostics remains challenging. With our approach, we cross-reference the GWAS findings for atherosclerotic disease with scRNA-seq data of disease-relevant tissue and bring the GWAS findings closer to the functional and mechanistic studies.

Monocyte chemoattractant protein-1 (MCP-1) recruits monocytes to the atherosclerotic plaque. While experimental, genetic, and observational data support a key role of MCP-1 in atherosclerosis, the translational potential of targeting MCP-1 signaling for lowering vascular risk is limited by the lack of data on plaque MCP-1 activity in human atherosclerosis. Here, we measured MCP-1 levels in human plaque samples from 1,199 patients undergoing carotid endarterectomy and explored associations with histopathological, molecular, and clinical features of plaque vulnerability. MCP-1 plaque levels were associated with histopathological hallmarks of plaque vulnerability (large lipid core, low collagen, high macrophage burden, low smooth muscle cell burden, intraplaque hemorrhage) as well as with molecular markers of plaque inflammation and matrix turnover, clinical plaque instability, and periprocedural stroke during plaque removal. Collectively, our findings highlight a role of MCP-1 in human plaque vulnerability and suggest that interfering with MCP-1 signaling in patients with established atherosclerosis could lower vascular risk.