Single-Cell Multimodal Profiling Reveals a Novel CD26⁺ Fibroblast Subpopulation in Atherosclerosis

Atherosclerosis involves complex interactions between lipids, immune cells, vascular smooth muscle cells (VSMCs), and fibroblasts within the arterial wall. While significant advances in single-cell technologies have shed light on the roles of immune cells and VSMCs in plaque development, fibroblasts remain underexplored, leaving critical gaps in understanding their contributions to disease progression and plaque stability. Comprehensive characterization of fibroblast phenotypes in atherosclerosis is essential to unravel their diverse functions and to distinguish between subsets that may play protective versus pathogenic roles in the disease process.

Here, we utilized CITE-seq (Cellular Indexing of Transcriptomes and Epitopes by Sequencing) to comprehensively profile fibroblast diversity in a mouse model of atherosclerosis. Mice were fed an atherogenic diet for 0, 8, 19, and 26 weeks, representing distinct stages of disease progression, enabling a detailed phenotypic characterization of fibroblasts throughout the course of atherosclerosis development.

We identified four distinct fibroblast subpopulations, including a myofibroblast population closely resembling VSMC-derived chondromyocytes. The proportions of these fibroblast subsets exhibited a modest decline as atherosclerosis progressed. Through multimodal analysis, we identified CD26 as a highly expressed and specific marker for one of these fibroblast subpopulations, distinguishing it from other subsets. Using a combination of flow cytometry and immunohistochemistry, we demonstrated that CD26⁺ fibroblasts predominantly reside in the adventitia of healthy arteries. During atherosclerosis progression, these cells expand into the intima and primarily localize within the fibrous cap of the lesion.

Our multi-omic analysis highlights the phenotypic diversity and dynamic changes of fibroblasts during atherosclerosis progression. Among these, CD26+ fibroblasts emerge as a distinct subpopulation that expands within atherosclerotic lesions and may play a critical role in promoting plaque stability through their migration into the fibrous cap.