Possible Involvement of Skin-Resident Memory T Cells in Refractory Chronic Alopecia Areata

This study examines the involvement of skin-resident memory T (TRM) cells in refractory chronic alopecia areata (AA) by analyzing skin samples from 9 chronic and 5 acute AA patients. It reveals that chronic AA lesions have a higher presence of CD8+CD103+ and CD69+CD103+ TRM cells, which may contribute to the chronicity and treatment resistance of AA. Additionally, treatment-resistant cases show more FABP4+CD103+ T cells, which use fatty acids for survival. Baricitinib, a JAK1/2 inhibitor, was effective in reducing TRM cell infiltration and improving hair regrowth in a patient with intractable AA, suggesting its potential as a treatment. However, the findings are based on a single case, indicating the need for further research with a larger sample size.