A rare population of TGFB-expressing resident macrophages undergoes macrophage to myofibroblast transition during wound repair 2260

Abstract Description Precise regulation of macrophage phenotype is essential for normal wound healing, and macrophage to myofibroblast transition (MMT) has been reported in various diseases. We used spatial sequencing of human wounds to characterize macrophages undergoing MMT during wound healing. Using markers CD14, CD16, and CD68, we identified 13,226 total macrophages. Out of these, we used several markers (FCGR1A, ITGAM, MERTK, CCR2, SIGLEC1, CX3CR1, CD163, LYVE1, MRC1, TIMD4, and CD9) to identify 579 tissue resident macrophages (4.4% of total macrophages). Tissue resident macrophages had increased TGFB1 expression compared to non-resident macrophages. Additionally, neighbor analysis revealed more fibroblasts in proximity to resident macrophages than non-resident macrophages. Finally, flow cytometry of whole wounds from GFP-Col1a1 reporter mice revealed increased GFP expression in the CD3-CD19-Ly6G-CD11b+F4/80+ resident macrophage population compared to the CD3-CD19-NK1.1-Ly6G-CD11b+Ly6C+ non-resident population. The F4/80+GFP+ subpopulation increased from day 5 to day 7 post-wounding. Finally, flow cytometry of wounds isolated from GFP-Col1a1 mice on normal diet (ND) versus high-fat (diabetic) diet revealed significantly fewer CD19-Ly6G-CD11b+F4/80+GFP+ macrophages from mice on a diabetic diet (2%) compared to ND wounds (15%). Our findings identify a rare subpopulation of TGFb-expressing resident macrophages that undergoes MMT during wound healing and is decreased in diabetic wounds. Funding Sources NIH R01-HL137919, NIH R01-DK124290-01, NIH R01-AR079863-01, NIH R01-HL156274-01A1, NIH R01-DK 127531-01A1, Doris Duke Foundation CSDA 2017079, F32-DK131799-01, American College of Surgeons Resident Research Award, Vascular and Endovascular Surgical Society Resident Research Award Topic Categories Immune Mechanisms of Human Disease (HUM)