Th17 cells and activated dendritic cells are increased in vitiligo lesions

Background

Vitiligo is a common skin disorder, characterized by progressive skinde-pigmentation due to the loss of cutaneous melanocytes. The exact cause ofmelanocyte loss remains unclear, but a large number of observations havepointed to the important role of cellular immunity in vitiligopathogenesis.

Methodology/Principal Findings

In this study, we characterized T cell and inflammation-related dermaldendritic cell (DC) subsets in pigmented non-lesional, leading edge anddepigmented lesional vitiligo skin. By immunohistochemistry staining, weobserved enhanced populations of CD11c+ myeloid dermal DCs andCD207+ Langerhans cells in leading edge vitiligo biopsies.DC-LAMP+ and CD1c+ sub-populations of dermal DCs expandedsignificantly in leading edge and lesional vitiligo skin. We also detectedelevated tissue mRNA levels of IL-17A in leading edge skin biopsies ofvitiligo patients, as well as IL-17A positive T cells byimmunohistochemistry and immunofluorescence. Langerhans cells with activatedinflammasomes were also noted in lesional vitiligo skin, along withincreased IL-1ß mRNA, which suggest the potential of Langerhans cellsto drive Th17 activation in vitiligo.

Conclusions/Significance

These studies provided direct tissue evidence that implicates active Th17cells in vitiligo skin lesions. We characterized new cellular immuneelements, in the active margins of vitiligo lesions (e.g. populations ofepidermal and dermal dendritic cells subsets), which could potentially drivethe inflammatory responses.