Atherosclerosis is a chronic lipid-driven inflammatory condition underlying cardiovascular morbidity and mortality. Macrophages are central to plaque development, yet their lineage diversity and prognostic significance remain incompletely defined. The study, published in European Heart Journal, characterized macrophage subtypes in carotid plaques and evaluated their association with secondary major adverse cardiovascular events (MACE).

Single-cell RNA sequencing was performed on blood and plaque samples from 46 carotid endarterectomy patients enrolled in the AtheroExpress cohort. Bulk RNA sequencing data from 656 AtheroExpress patients were deconvoluted to assess cell-type associations with symptoms at surgery and 3-year MACE risk. Findings were validated in 82 patients from the Carotid Plaque Imaging Project.

Four major macrophage archetypes were identified: inflammatory macrophages, lipid-associated macrophages (LAMs), tissue-resident-like LAMs, and inflammatory LAMs. Trajectory and fate analyses demonstrated derivation from both classical and non-classical monocytes and showed differentiation into inflammatory LAMs via inflammatory or resident-like LAM and LAM stages. Deconvolution of the AtheroExpress bulk RNA-seq cohort demonstrated that macrophages were the only cell population significantly associated with both symptomatic presentation at surgery and increased risk of major adverse cardiovascular events during 3-year follow-up. Within macrophages, predominantly LAM and inflammatory LAM foam cell markers, including PLIN2 and TREM1, were associated with increased 3-year MACE risk. These associations were validated in the Carotid Plaque Imaging Project cohort.

Distinct macrophage subtypes in atherosclerotic plaques were associated with future cardiovascular events. These findings demonstrate their clinical significance and association with risk of secondary MACE.