Integration of Single-Cell and Spatial Transcriptomics With Experimental Validation Uncovers Macrophage Diversity and Spatial Landscape in Carotid Atherosclerosis.

The core pathogenesis of carotid atherosclerosis (CAS) lies in the rupture of vulnerable plaques, with macrophages (MC) playing a critical role in plaque progression and destabilization. However, the functional characteristics of MC subpopulations in CAS remain poorly understood. This study systematically investigates the cellular composition of CAS and the regulatory mechanisms of MC by integrating single-cell RNA sequencing (scRNA-seq), in vitro models, and spatial transcriptomics. Differentially expressed genes upregulated in MC were significantly enriched in multiple signaling pathways, including Lipid and Atherosclerosis, Lysosome, and Antigen Processing and Presentation. Gene Set Variation Analysis (GSVA) revealed higher MC scores for Angiogenesis and Lipid Metabolism in the atherosclerotic core (AC). A total of seven distinct MC subtypes were identified. Pseudotime analysis indicated that IGSF21+ MC constitute the initial cell population, while FABP4+ MC represent the terminal cells along the trajectory. An in vitro atherosclerosis model was established to validate the diagnostic value of SPP1, FTH1, and FTL. Spatial transcriptomics further revealed the spatial connection patterns of the SPP1 signaling pathway network across different cell types. This study provides novel molecular insights into the pathogenesis of CAS and lays the groundwork for developing diagnostic biomarkers and therapeutic targets.