Disturbed Blood Flow Plus High Cholesterol Turns Artery-Lining Cells Into Immune-Like and Foam Cells
Mouse single-cell data suggest disturbed flow and high cholesterol together reprogram endothelial cells into immune-like and foam-like cells that drive plaque.
Resumo
Atherosclerosis forms preferentially where blood flow is disturbed, even though high cholesterol affects the whole body. Using a mouse partial carotid ligation model, researchers combined disturbed flow with PCSK9-induced hypercholesterolaemia and a Western diet. Single-cell RNA sequencing of 98,553 cells from 95 mice suggested a two-hit process. Disturbed flow alone partially reprograms endothelial cells toward inflammation, mesenchymal-like states and a partial immune-like state. With high cholesterol added, some endothelial cells appear to transition fully into immune-like cells and into foam-like cells resembling those from smooth muscle cells and macrophages. Genetic lineage-tracing in endothelial-specific confetti mice, cultured human aortic endothelial cells, and reanalysis of human plaque datasets with immunostaining supported these findings. The work offers a cell-level roadmap for targeting flow-sensitive pathways, though it remains largely preclinical.
Resumo Detalhado
Atherosclerosis remains a leading cause of heart attack and stroke despite effective cholesterol-lowering drugs such as statins. Plaques form preferentially at curved and branched arterial sites exposed to disturbed flow (d-flow), while straight regions with stable flow are relatively protected, even in people with high cholesterol. Understanding how flow and cholesterol interact at the cellular level could reveal therapeutic targets beyond lipid lowering.
The team used the mouse partial carotid ligation (PCL) model, which exposes the left common carotid artery to d-flow while the right carotid serves as a stable-flow control in the same animal. Hypercholesterolaemia was induced with AAV8-PCSK9 gene delivery plus a Western diet. They compared d-flow alone, hypercholesterolaemia alone, and the combination. Single-cell RNA sequencing was performed on carotid arteries at 2 and 4 weeks, with a prior dataset (d-flow alone, normal cholesterol) integrated for comparison. The final atlas had 98,553 cells from 95 mice and 25 clusters, including 5 endothelial, 3 smooth muscle and 5 macrophage clusters, plus fibroblasts, T cells, NK cells, dendritic cells, neutrophils and B cells.
Plaques developed only when d-flow and hypercholesterolaemia were combined, not with either alone. The single-cell data supported a two-hit hypothesis of flow-induced reprogramming of endothelial cells (FIRE). D-flow alone drove inflammation, endothelial-to-mesenchymal transition (EndMT) and only partial endothelial-to-immune-cell-like transition (EndIT). With hypercholesterolaemia added, the data suggested a full EndIT and a newly proposed endothelial-to-foam-cell-like transition (EndFT). Endothelial cells with foam-cell features had transcriptomic profiles strikingly similar to foam cells derived from smooth muscle cells and macrophages.
The authors tested this in several ways. Lineage-tracing with endothelial-specific confetti mice at 4 weeks, stained for canonical protein and lipid markers, supported EndIT and EndFT. Human aortic endothelial cells exposed to d-flow, high cholesterol and proinflammatory cytokines identified in the sequencing data showed EndIT and EndFT markers at the mRNA, protein and functional levels. Reanalysis of two public human plaque single-cell datasets, along with immunostaining of human coronary plaques, suggested FIRE also occurs in human disease.
These findings could shift how atherosclerosis is understood, from endothelial dysfunction alone to endothelial cells acting as a source of plaque immune-like and foam cells. The atlas may help prioritize flow-sensitive genes and pathways for drug development. Caveats: the work is mostly in mice and cultured cells, the human evidence is correlative, and the proportion of plaque foam or immune cells truly derived from endothelium in people is unknown. The provided text was truncated after the methods, so details of the results come mainly from the abstract.
Principais Descobertas
- Plaque formed only when disturbed flow and hypercholesterolaemia were combined, not with either alone, supporting a two-hit model.
- scRNA-seq of 98,553 cells from 95 mice identified 25 clusters, including 5 endothelial, 3 smooth muscle and 5 macrophage clusters.
- Disturbed flow alone drove inflammation, EndMT and partial EndIT; added hypercholesterolaemia produced full EndIT and a proposed endothelial-to-foam-cell transition (EndFT).
- Endothelial-derived foam-like cells shared transcriptomic profiles with foam cells from smooth muscle cells and macrophages.
- Confetti lineage-tracing, human aortic endothelial cell experiments and human plaque datasets support FIRE, EndIT and EndFT.
Metodologia
Male C57BL/6 mice received AAV8-PCSK9 and a Western diet, with partial carotid ligation to create disturbed flow in the left carotid and stable flow in the right. Carotid cells were profiled by 10x Genomics scRNA-seq at 2 and 4 weeks and integrated with a prior dataset using Seurat RPCA. Findings were tested with endothelial-specific confetti lineage-tracing, human aortic endothelial cells under disturbed flow, cholesterol and cytokines, and public human plaque datasets with human coronary immunostaining.
Limitações do Estudo
Evidence is mainly from a mouse model with an artificial ligation and PCSK9-induced hypercholesterolaemia, plus in vitro cell studies, so translation to human disease is unproven. Human validation is correlative (reanalysed datasets and immunostaining), and the true fraction of plaque cells of endothelial origin remains uncertain. The supplied text was cut off after the methods, so this summary relies largely on the abstract for results.
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