Photo by: James Heilman, MD, via Wikimedia Commons
Two immune checkpoints, Cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) and programmed death-1 (PD-1), appear to be present in the inflammatory infiltrate of active non-segmental vitiligo (NSV), according to findings published online ahead of print in International Journal of Dermatology (June 18, 2020). In the paper, the authors write: “Vitiligo is a depigmentary skin disfigurement resulting from destruction of melanocytes caused by a possible malfunctioning immunity. This destruction could be linked to an aberrant T-cell-mediated immune response.” Because both CTLA-4 and PD-1 are capable of down-regulating T-cell immune functions, the researchers conducted a pilot study to evaluate the expression of these two checkpoints in active vitiligo skin. In the study, investigators obtained skin biopsies from 30 patients with NSV. They then used digital imaging to evaluate CTLA-4 and PD-1 immunohistochemistry expression in the mononuclear inflammatory infiltrates of the biopsies. They found that inflammatory infiltrates were significantly abundant in both marginal and lesional skin samples when compared to non-lesional ones. As well, the marginal infiltrates were significantly abundant when compared to the lesional ones. Both of the checkpoints were significantly expressed in the marginal and lesional infiltrates when compared to non-lesional skin. In particular, the marginal expression of PD-1 was significantly higher than the lesional expression. No similar significant difference in CTLA-4 expression was found between the marginal and lesional infiltrates. Investigators also found significant positive correlations between the expressions of PD-1 and CTLA-4 in marginal and lesional infiltrates. The authors note that while these findings are interesting, further studies will be needed to confirm their significance in the development or limitation of vitiligo.