Expression data from Staphylococcus aureus and Phosphate buffered saline (PBS) treated mouse wound bed. Expression data from Staphylococcus aureus and Phosphate buffered saline (PBS) treated mouse wound bed

Environmental factors that enhance regeneration are largely unknown. We hypothesized that skin bacteria modulate regeneration. Here, we assessed low, medium, and high levels of bacterial burden in Wound Induced Hair follicle Neogenesis (WIHN), a rare adult organogenesis model. WIHN levels and stem cell markers indeed correlated with bacterial counts, being lowest in germ free (GF), intermediate in conventional specific pathogen free (SPF), and highest even in mice infected with pathogenic Staphylococcus aureus. We identified IL-1β and keratinocyte-dependent IL-1R-MyD88 signaling as necessary and sufficient for bacteria to promote regeneration. Finally, in a small clinical trial, we found that a topical broad-spectrum antibiotic slowed skin wound healing. These results counter conventional notions that infection inhibits regeneration and the need for full sterility of small wounds. Overall design: 21-day-old, 8 to 12 -gram male and female mice in their first telogen phase were selected. Mice were anesthetized with vaporizing anesthesia (Baxter, Isoflurane), shaved, and denuded of 1.44 cm² full thickness skin using sterile procedures. PBS and 1e7 /100ul S. aureus were injected under the scab on wound day3.