APM⁺ macrophages associated with plaque vulnerability via MIF-CD74 signaling: a multi-omics study.

BACKGROUND: Atherosclerosis (AS) is a chronic vascular disease and the principal cause leading to ischemic cardiomyopathy (ICM). It involves complex metabolic dysregulation beyond the resolution of single-omics. Emerging evidence implicates arginine-proline metabolism (APM) in driving inflammation and impairing efferocytosis, yet the cellular basis of plaque instability remains elusive. METHODS: We employed a five-stage analytical framework. First, metabolomic profiling revealed shared pathways between AS and ICM. Second, single-cell RNA sequencing identified APM-enriched macrophage subtypes in both diseases. Pseudotime analysis, Scissor algorithm, and cell-cell communication analyses linked these subtypes to APM signaling, stroke prognosis, and key ligand-receptor interactions. Third, cNMF and unsupervised clustering defined APM-related gene signatures in macrophages, validated by survival analysis. Fourth, spatial transcriptomics confirmed their spatial distribution and colocalization within unstable plaques. Finally, key biomarkers were validated in atherosclerotic lesions using ApoE(-/-) mouse. RESULTS: Metabolomic profiling revealed APM as a shared dysregulated pathway in AS and ICM. We identified a macrophage subset (SPP1⁺ macrophages and mono-macrophages), termed APM_high macrophages, enriched in the fibrous cap and characterized by elevated collagenase activity, heightened inflammation, and disrupted cholesterol homeostasis. Spatial and cell-cell communication analyses revealed strong interactions with dendritic cells via the MIF-(CD74 + CXCR4) axis, potentially contributing to plaque destabilization. Transcriptomic clustering uncovered a high-APM plaque subtype associated with worse ischemic outcomes. Six diagnostic biomarkers were identified through machine learning and validated across multiple cohorts and in ApoE(-/-) mouse. CONCLUSION: In summary, our study decodes the metabolic basis of inflammation shared between AS and ICM, suggesting an APM_high macrophage-centered regulatory axis across multiple omics layers. This work advances our understanding of the cardio-metabolic axis and suggests new avenues for targeted therapy.