CXCR3 Blockade Inhibits T Cell Migration into the Skin and Prevents Development of Alopecia Areata.

Alopecia areata (AA) is an autoimmune disease of the hair follicle that results in hair loss of varying severity. Recently, we showed that IFN-γ-producing NKG2D(+)CD8(+) T cells actively infiltrate the hair follicle and are responsible for its destruction in C3H/HeJ AA mice. Our transcriptional profiling of human and mouse alopecic skin showed that the IFN pathway is the dominant signaling pathway involved in AA. We showed that IFN-inducible chemokines (CXCL9/10/11) are markedly upregulated in the skin of AA lesions, and further, that the IFN-inducible chemokine receptor, CXCR3, is upregulated on alopecic effector T cells. To demonstrate whether CXCL9/10/11 chemokines were required for development of AA, we treated mice with blocking Abs to CXCR3, which prevented the development of AA in the graft model, inhibiting the accumulation of NKG2D(+)CD8(+) T cells in the skin and cutaneous lymph nodes. These data demonstrate proof of concept that interfering with the Tc1 response in AA via blockade of IFN-inducible chemokines can prevent the onset of AA. CXCR3 blockade could be approached clinically in human AA with either biologic or small-molecule inhibition, the latter being particularly intriguing as a topical therapeutic.