Single Cell Landscape of Left Atria Reveals Amphiregulin and Insulin-like Growth Factor 1 as Surrogate Markers in Patients with Atrial Fibrillation.

Atrial fibrillation (AF) is strongly associated with strokes, heart failure, and increased mortality. Inflammation plays a role in the pathophysiology of AF; however, how inflammation in AF is sustained and induces fibrosis is unclear. Therefore, this study aimed to identify the characteristic monocyte–macrophage heterogeneity and the cell–cell interactions between immune and non-immune cells at a single cell level in the left atrial (LA) tissues of patients with AF who underwent LA appendectomies. Myeloid cells were divided into five macrophage clusters, TNF+, two IL1B+, TREM2+, LYVE1+ resident macrophages, three monocyte clusters, five dendritic cell clusters, neutrophils, and mast cells. The CellChat analysis revealed that IL1B+ macrophages send epidermal growth factor (EGF) signalling to fibroblasts and resident macrophages send IGF1 singalling to cardiomyocytes. When compared to openly published control samples, Amphiregulin (AREG) was the most upregulated gene in monocytes and monocyte-derived IL1B+ macrophages in the AF group. We also found that AREG levels in serum were higher in patients with AF than controls. EGF signalling from IL1B+ macrophages could be therapeutic targets for AF, and AREG could be a functional biomarker for AF.