Cutaneous Expression of A Disintegrin-like and Metalloprotease domain containing Thrombospondin Type 1 motif-like 5 (ADAMTSL5) in Psoriasis goes beyond Melanocytes

A Disintegrin-like and Metalloprotease domain containing Thrombospondin type 1 motif-like 5 (ADAMTSL5) is a melanocyte-derived protein that has recently been implicated as an activating antigen for IL-17-producing T cells in psoriasis. There is a potential disconnect between the basal location of the melanocytes in the epidermis and the fact that T-cell infiltrates are seen mostly scattered in the epidermis with very large infiltrates in the dermis. Thus, we hypothesized that ADAMTSL5 may be expressed in other cells aside from melanocytes in skin. To further investigate the cutaneous expression of ADAMTSL5, we performed immunohistochemistry staining on lesional and nonlesional skin biopsies from psoriasis patients using three different commercially available antibodies. We confirmed that all ADAMTSL5 antibodies reacted with epidermal melanocytes. However, we also observed a strong expression of this protein in keratinocytes throughout the epidermis, and scattered expression in some dermal blood vessels and other perivascular dermal cells. Overall, the pattern of ADAMTSL5 expression is very similar to the infiltrating pattern of T-cells and dendritic cells in psoriasis lesions.