Melanocyte antigen triggers autoimmunity in human psoriasis.
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Arakawa A, Siewert K, Stohr J, Besgen P, Kim SM, Ruhl G, Nickel J, Vollmer S, Thomas P, Krebs S, Pinkert S, Spannagl M, Held K, Kammerbauer C, Besch R, Dornmair K, Prinz JC
Melanocyte antigen triggers autoimmunity in human psoriasis.
J Exp Med. 2015 Dec 14;212(13):2203-12. doi: 10.1084/jem.20151093. Epub 2015 Nov 30.
- PubMed ID
- 26621454 [ View in PubMed]
- Abstract
Psoriasis vulgaris is a common T cell-mediated inflammatory skin disease with a suspected autoimmune pathogenesis. The human leukocyte antigen (HLA) class I allele, HLA-C*06:02, is the main psoriasis risk gene. Epidermal CD8(+) T cells are essential for psoriasis development. Functional implications of HLA-C*06:02 and mechanisms of lesional T cell activation in psoriasis, however, remained elusive. Here we identify melanocytes as skin-specific target cells of an HLA-C*06:02-restricted psoriatic T cell response. We found that a Valpha3S1/Vbeta13S1 T cell receptor (TCR), which we had reconstituted from an epidermal CD8(+) T cell clone of an HLA-C*06:02-positive psoriasis patient specifically recognizes HLA-C*06:02-positive melanocytes. Through peptide library screening, we identified ADAMTS-like protein 5 (ADAMTSL5) as an HLA-C*06:02-presented melanocytic autoantigen of the Valpha3S1/Vbeta13S1 TCR. Consistent with the Valpha3S1/Vbeta13S1-TCR reactivity, we observed numerous CD8(+) T cells in psoriasis lesions attacking melanocytes, the only epidermal cells expressing ADAMTSL5. Furthermore, ADAMTSL5 stimulation induced the psoriasis signature cytokine, IL-17A, in CD8(+) T cells from psoriasis patients only, supporting a role as psoriatic autoantigen. This unbiased analysis of a TCR obtained directly from tissue-infiltrating CD8(+) T cells reveals that in psoriasis HLA-C*06:02 directs an autoimmune response against melanocytes through autoantigen presentation. We propose that HLA-C*06:02 may predispose to psoriasis via this newly identified autoimmune pathway.