Abstract Body (Do not enter title and authors here): Background: Excessive lipid aggregation in macrophages triggers foam cell formation, contributing to arterial plaque development. This underlies the chronic vascular condition of atherosclerosis like coronary heart disease and ischemic stroke. Epsins, endocytic adaptor proteins, are recognized as key accelerators of atherosclerosis progression, particularly in individuals adhering to a Western diet (WD). However, the intricate molecular mechanisms governing the role of epsins in foam cell formation, disease progression, and potential therapeutic interventions remain elusive. Here, we aim to probe the metabolic regulatory functions of epsins in atherosclerosis and design the potential treatment strategies.
Methods: We established mouse models fed a WD (16 weeks), including ApoE-deficient (ApoE^-/-) mice and macrophage-specific deletion of epsin in ApoE-deficient backgrounds (LysM-DKO/ApoE^-/-). Foam cell formation is dramatically hindered in WD-fed LysM-DKO/ApoE^-/- compared to ApoE^-/- mice.
Results: Single-cell transcriptomic profiling of aorta cells revealed 20 cell types, including seven VSMC subtypes, five macrophage subtypes, endothelial cells, and others. Pathway enrichment analysis showed that modulating VSMC1 is involved in inflammation and migration, while VSMC2 is associated with VSMC phenotype switching. We observed increased populations of modulating VSMC1, VSMC2, foamy-Trem2, and inflammatory macrophages in ApoE^-/- mice, which decreased significantly in epsin-deficient mice. The RNA velocity analysis revealed that modulating VSMC2 transitioned towards macrophages with probabilities of 0.7 in ApoE^-/- mice and 0.01 in LysM-DKO/ApoE^-/- mice. Additionally, epsin deletion reversed endothelial cell dysfunction by preventing the endothelial-to-mesenchymal transition. Using MEBOCOST tool, we identified the cholesterol, glucose mediated cell-signals are downregulated in LysM-DKO/ApoE^-/-. Moreover, enhanced inflammatory signals via ligands such as Il1b and C1qa in VSMCs are downregulated when epsin is depleted.
Conclusion: Single-cell data analysis reveals that epsin deletion reduces foam cell formation and rewires VSMC cells function by inhibiting VSMC2 to macrophage transition. Cholesterol and glucose-mediated metabolic signals play a pivotal role in atherosclerotic lesion formation. Epsin deletion diminishes these metabolic, and inflammatory signals. Therefore, targeting epsin could offer a novel therapeutic strategy for treating atherosclerosis.