Effect of Immunosuppressive PPIase Inhibitors, Cyclosporin A, FK506, Ascomycin, and Rapamycin on Hair Growth Initiation

The document reports on the effects of various immunosuppressive PPlase inhibitors on hair growth initiation in mice. Cyclosporin A (CSA) and FK506 (FK) were found to induce new hair growth in mice 12 days after a single topical application during the telogen phase of the hair cycle. However, ascomycin (Asc) and rapamycin (Rap) did not initiate new anagen hairs even at higher doses. Additionally, Asc inhibited the anagen induction by FK but not by CSA, while Rap inhibited new hair growth induced by both CSA and FK. These results suggest that the inhibition of PPlase is not essential for the initiation of the hair cycle in mice and that the induction of new hair growth by CSA and FK is likely due to direct activation of hair-related cells rather than inactivation of the immune system. The study also indicates that calcineurin or IL-2 does not seem to be involved in this process.