Bacteria induce skin regeneration via IL-1β signaling

Environmental factors that enhance regeneration are largely unknown. The immune system and microbiome are attributed roles in repairing and regenerating structure but their precise interplay is unclear. Here, we assessed the function of skin bacteria in wound healing and wound-induced hair follicle neogenesis (WIHN), a rare adult organogenesis model. WIHN levels and stem cell markers correlate with bacterial counts, being lowest in germ-free (GF), intermediate in conventional specific pathogen-free (SPF), and highest in wildtype mice, even those infected with pathogenic Staphylococcus aureus. Reducing skin microbiota via cage changes or topical antibiotics decreased WIHN. Inflammatory cytokine IL-1 beta and keratinocyte-dependent IL-1R-MyD88 signaling are necessary and sufficient for bacteria to promote regeneration. Finally, in a small trial, a topical broad-spectrum antibiotic also slowed skin wound healing in adult volunteers. These results demonstrate a role for IL-1 beta to control morphogenesis and support the need to reconsider routine applications of topical prophylactic antibiotics.

Automated summary

The study evaluated the role of skin bacteria in wound healing and hair follicle regeneration, finding a correlation between bacterial counts and WIHN levels. Reduction of skin microbiota decreased WIHN, while IL-1 beta and IL-1R-MyD88 signaling played crucial roles in bacteria-promoted regeneration.