Cell types activated in mouse muscle by TLR7/8 stimulation

ScRNA-seq analysis of 11,450 cells from mouse muscle tissue sections following R848 injection identified 19 cell clusters, including four fibroblast, two endothelial cell, two macrophage, and two T cell subpopulations. To identify which cell populations were activated downstream of TLR7/8, interferon gene signature (IFN-GS) and NF-κB-gene signature (NF-κB-GS) scores were calculated and heat maps generated. There was a noticeable IFN response in most cell populations, with the greatest IFN-GS induction in neutrophils, endothelial cells and macrophages, and some response in T cells. However, IFN induction was not observed in any muscle cell type after R848 injection. The NF-κB-GS was expressed under basal conditions in many cell populations and was induced by R848 most in macrophages and neutrophils, with some increase also seen in endothelial cells.