Injury-Induced Interleukin-1 Alpha Promotes Lgr5 Hair Follicle Stem Cells Regeneration and Proliferation via Regulating Regenerative Microenvironment in Mice

The study found that the protein interleukin-1 alpha (IL-1α) plays a crucial role in hair follicle regeneration and stem cell proliferation in mice. Younger mice (3 weeks old) were found to regenerate hair follicles and Lgr5 hair follicle stem cells more effectively than older mice (7 weeks old), a process influenced by immune cells, cytokines, and IL-1α levels. Injecting IL-1α induced hair follicle and stem cell regeneration in 3-week-old mice with a wound and promoted stem cell activation and proliferation in 7-week-old mice without a wound. The effects of IL-1α were inhibited by dexamethasone and TEMPOL. IL-1α also increased skin thickness and promoted the proliferation of human epidermal keratinocyte line and skin-derived precursors. The study concludes that IL-1α promotes hair follicle regeneration by modulating inflammatory cells and oxidative stress-induced stem cell regeneration, and promoting skin cell population proliferation.