Resident memory T cells (TRM) are a critical component of the tissue immune response but are also implicated in the physiopathology of cutaneous chronic inflammatory diseases, such as vitiligo. In this depigmenting disease characterized by the loss of epidermal melanocytes, the involvement of skin TRM with a type-1 skewed immune response (production of IFNγ and TNFα) in lesions is commonly admitted. Our recent data suggest an additional role of a type-2 immune response with local production of IL-13. In addition, increasing evidence suggest that non-lesional (NL) skin in cutaneous inflammatory diseases like psoriasis or atopic dermatitis already display an altered immune response. Yet, little is known regarding the T cell immune response NL skin of vitiligo patients. We aimed to decipher the phenotype and function of the TRM infiltrating normal appearing skin of vitiligo patients. While infiltration of CD8 T cells was more prominent in vitiligo perilesional (PL) skin, NL and PL skin displayed similar subsets of TRM defined by the markers CD69, CD103 and CD49a. However, skin T cells isolated from PL vitiligo skin showed a decreased expression of PD-1 which may be responsible of a breakdown of a quiescent state of TRM in NL areas. Interestingly, following ex vivo T cell activation, NL skin displayed an intermediate inflammatory transcriptional profile compared to healthy skin and PL vitiligo skin. In addition, activated NL vitiligo skin T cells produced both type-1 and type-2 related cytokines (including IL-13), albeit at lower levels than activated vitiligo PL skin T cells. Interestingly, IL-13 was implicated in the inflammatory response of epidermal cells by inducing CCL18 production. Taken together, our results suggest that “pathogenic” TRM are already present in pigmented areas in a quiescent state and could contribute to inflammatory flare-ups and relapse of vitiligo.

ESDR320 - Looking at the memory response in normal appearing skin of vitiligo

The scientific meeting of the European Society for Dermatological Research (ESDR) is held yearly, usually in September. With an international attendance of more than 1000 skin scientists from around the globe, the four-day event includes short oral presentations from peer-reviewed abstracts, keynote lectures from international experts, sponsored symposia, satellite programs, educational events as well as an important focus on posters, networking and building collaborations amongst scientists. For more information about this year’s meeting visit our website.