Baricitinib is Effective in Treating Progressing Vitiligo in vivo and in vitro

OBJECTIVE: To evaluate the clinical efficacy and safety of baricitinib, a Janus kinase (JAK) inhibitor, in treating patient with progressing vitiligo, and to further explore the regulation of baricitinib on melanocytes (MCs) in vitro. METHODS: Four patients with progressing vitiligo were treated with oral baricitinib for a total of 12 weeks. MCs were cultured in vitro and irradiated by high-dose ultraviolet B (UVB, 150mJ/cm(2)) to make an MC damaged model (MC-Ds). Baricitinib was added at a final concentration of 25 μM. Dopamine staining and NaOH method were used to measure the tyrosinase activity and melanin level, respectively, real-time quantitative polymerase chain reaction (RT-qPCR) was used to measure the mRNA levels of tyrosinase (TYR), tyrosinase-related protein-1 (TRP-1). RESULTS: Significant re-pigmentation was observed in the week 12 without obvious side effects. Depigmentation occurred in 2 patients at the 3-month follow-up. Laboratory research found that higher doses of UVB irradiation (150mJ/cm(2)) could decrease melanin content of MCs, baricitinib (25 μM) could significantly promote tyrosinase activity, melanin content, and TYR, TRP-1 gene expression of MC-Ds. CONCLUSION: Our preliminary study showed that baricitinib was effective and safe in treating progressing vitiligo. Baricitinib could promote tyrosinase activity, melanin content and TYR, TRP1 gene expression of MC-Ds in vitro.