Single-Cell RNA-Seq Reveals a Crosstalk between Hyaluronan Receptor LYVE-1-Expressing Macrophages and Vascular Smooth Muscle Cells.

Fabienne Burger,Karim J Brandt,Daniela Baptista,François Mach,Kapka Miteva,Aline Roth,Fabrizio Montecucco,Rafaela Fernandes Da Silva

doi:10.3390/cells11030411

Abstract

Background: Atherosclerosis is a chronic inflammatory disease where macrophages participate in the progression of the disease. However, the role of resident-like macrophages (res-like) in the atherosclerotic aorta is not completely understood. Methods: A single-cell RNA sequencing analysis of CD45+ leukocytes in the atherosclerotic aorta of apolipoprotein E–deficient (Apoe−/−) mice on a normal cholesterol diet (NCD) or a high cholesterol diet (HCD), respecting the side-to-specific predisposition to atherosclerosis, was performed. A population of res-like macrophages expressing hyaluronan receptor LYVE-1 was investigated via flow cytometry, co-culture experiments, and immunofluorescence in human atherosclerotic plaques from carotid artery disease patients (CAD). Results: We identified 12 principal leukocyte clusters with distinct atherosclerosis disease-relevant gene expression signatures. LYVE-1+ res-like macrophages, expressing a high level of CC motif chemokine ligand 24 (CCL24, eotaxin-2), expanded under hypercholesteremia in Apoe−/− mice and promoted VSMC phenotypic modulation to osteoblast/chondrocyte-like cells, ex vivo, in a CCL24-dependent manner. Moreover, the abundance of LYVE-1+CCL24+ macrophages and elevated systemic levels of CCL24 were associated with vascular calcification and CAD events. Conclusions: LYVE-1 res-like macrophages, via the secretion of CCL24, promote the transdifferentiation of VSMC to osteogenic-like cells with a possible role in vascular calcification and likely a detrimental role in atherosclerotic plaque destabilization.

Highlights

Macrophages represent an immune cell population of major interest in the progression of chronic inflammation-driven diseases, such as atherosclerosis [1]
The Fluidigm C1 platform for RNA sequencing of single cells was used to reveal the transcriptional profiles of viable individual CD45+ aorta cells isolated from the arch and root (AA&R) and descending thoracic aorta (DT) aortas of Apoe−/− mice, fed either an normal cholesterol diet (NCD) for 16 weeks or an high cholesterol diet (HCD) for 11 weeks (Figure 1A)
Among the gene sets revealed by the GO term enrichment analysis of the cells derived from the DT aortas of Apoe−/− mice on HCD versus NCD, there were genes involved in T-cell activation, the positive regulation of defense response, the regulation of the immune effector process, the positive regulation of cytokine production, and the regulation of protein serine/threonine kinase activity, which could have an important implications for the regulation of the T-cell response [41] (Figure 1F)

Summary

Introduction

Macrophages represent an immune cell population of major interest in the progression of chronic inflammation-driven diseases, such as atherosclerosis [1]. Three macrophage subsets have been shown to express Lyve in atherosclerotic plaques of Ldlr−/− mice using scRNAseq [6] It has been suggested that atherosclerotic aortas contain resident macrophages originating from an embryonic pool, which, upon atherosclerosis development, are replaced by, or accompanied by, recruited monocyte-derived macrophages that adopt a resident-like macrophage phenotype and who play a role in endocytosis [7]. A population of res-like macrophages expressing hyaluronan receptor LYVE-1 was investigated via flow cytometry, co-culture experiments, and immunofluorescence in human atherosclerotic plaques from carotid artery disease patients (CAD). LYVE-1+ res-like macrophages, expressing a high level of CC motif chemokine ligand 24 (CCL24, eotaxin-2), expanded under hypercholesteremia in Apoe−/− mice and promoted VSMC phenotypic modulation to osteoblast/chondrocyte-like cells, ex vivo, in a CCL24-dependent manner. Conclusions: LYVE-1 res-like macrophages, via the secretion of CCL24, promote the transdifferentiation of VSMC to osteogenic-like cells with a possible role in vascular calcification and likely a detrimental role in atherosclerotic plaque destabilization

Methods

Results

Conclusion