Abstract
INTRODUCTION: Cardiovascular disease (CVD) caused by atherosclerosis (AS) remains the leading cause of mortality in developed countries. Understanding cellular heterogeneity within the inflammatory microenvironment is crucial for advancing disease management strategies. This study investigates the regulatory functions of distinct cell populations in AS pathogenesis, focusing on the interaction between vascular smooth muscle cell (VSMC)-derived ITLN1(+) foam cells and SPP1(+) FABP5(+) macrophages. METHODS: We employed single-cell RNA sequencing to characterize cell populations within AS plaques. Correlation analyses and the CellChat package were utilized to elucidate intercellular communication networks among various cell types. The functional roles of key subsets of macrophages and VSMCs were assessed using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses. Pseudotime trajectory analysis was conducted to explore the dynamics of VSMC differentiation. Additionally, spatial transcriptomics analysis was used to demonstrate the physical interactions between different cell subpopulations. RESULTS: We identified significant infiltration of macrophage clusters in AS, with SPP1(+) FABP5(+) macrophages being highly enriched in AS plaques. These macrophages were associated with lipid transport, storage, and cell migration pathways. A distinct subset of ITLN1(+) foam cells derived from VSMCs exhibited robust expression of foam cell markers and lipid metabolism-related genes. Pseudotime trajectory analysis indicated that ITLN1(+) foam cells represent a terminal stage of VSMC differentiation, characterized by elevated expression of genes linked to lipid synthesis and AS progression. Spatial transcriptomics and CellChat analysis revealed a significant interaction between ITLN1(+) foam cells and SPP1(+) FABP5(+) macrophages, mediated by the MIF-(CD74 + CD44) and SPP1-CD44 ligand-receptor axes. DISCUSSION: Our findings underscore the critical crosstalk between ITLN1(+) foam cells and SPP1(+) macrophages in promoting lipid accumulation and AS progression. Targeting this cell-cell interaction may offer new therapeutic avenues for managing atherosclerosis. Further validation of these mechanisms is necessary to develop effective immunotherapeutic strategies against AS.