Hair growth is induced by blockade of macrophage-derived oncostatin M and JAK-STAT5 signaling in hair follicle stem cells.

We also show that OSM is sufficient for maintaining quiescence of hair follicle stem cells (HFSCs), and OSMRß-JAK-STAT5 signaling is necessary for maintaining the resting phase of the hair cycle (telogen). Using single-cell RNA sequencing, we identify the source of OSM to be a distinct subset of TREM2+ macrophages that predominate during early telogen. Moreover, inhibition of macrophages during telogen by genetic ablation, neutralizing antibodies and small-molecule inhibitors was sufficient to induce anagen. Overall design: Single-cell RNA sequencing of CD45+ immune cells at 4 timepoints during murine telogen.