CXCR2 knockout promotes skin and hair regeneration without scarring

Mammals heal faster with imperfect fibrotic scars, while amphibians regenerate slower with scarless wound healing. These observations support the prevailing paradigm that speed of wound closure is inversely related to repair quality. Here we find evidence that this is a false trade-off. In multiple injury models, mice lacking CXCR2 (CXCR2-KO) globally improved both speed and quality of skin wound healing, including hair regeneration. We found CXCR2 primarily expressed in neutrophils, and injury induced neutrophils to secrete neutrophil extracellular traps (NETs). Mice engineered to be specifically deficient in myeloid CXCR2 or NET production partially recreated the phenotype with improved early speed of wound closure. Thus, CXCR2+ neutrophils regulate the speed of wound closure.