Selective Janus Kinase 1 Inhibition Resolves Inflammation and Restores Hair Growth Offering a Viable Treatment Option for Alopecia Areata

The study demonstrates that selective Janus kinase 1 (JAK1) inhibition is as effective as pan-JAK inhibition in resolving inflammation and restoring hair growth in alopecia areata (AA) with fewer side effects. Systemic JAK1 inhibition is necessary for efficacy, as local inhibition alone is insufficient unless it spills over systemically. The study found that a prolonged treatment period beyond remission is required to maintain the effect, as AA relapse occurs upon cessation of the 4-week treatment. RNA sequencing showed that JAK1 inhibition normalizes the skin transcriptome of AA mice, but systemic dysregulation persists, indicating the need for longer treatment to eliminate memory cells in secondary lymphoid organs and prevent relapse. The findings suggest that selective JAK1 inhibitors could offer a viable treatment option for AA with a potentially improved safety profile.