Frontal fibrosing alopecia (FFA) is the most common cicatricial alopecia, whose prevalence has greatly increased, mainly in post-menopausal women, results from irreversible epithelial hair follicle (HF) stem cell (eHFSC) damage. Exposure to ingredients commonly found in personal care products might trigger FFA-related immune responses. In fact, 76.2% of patients with FFA and/or LPP show type IV sensitization to allergens found in these products. Since the terpene fragrant, linalool, is one of the most common allergens identified in FFA patients, we have probed the hypothesis that linalool may promote bulge HF immune privilege (IP) collapse and/or eHFSC damage, i.e. core elements of FFA pathogenesis. Here we report preliminary evidence that exposing healthy human scalp HFs to 1% linalool in organ culture decreased the number of K15+ eHFSCs and their K15 expression, although bulge MHC class Ia expression was not upregulated. Importantly, linalool increased bulge expression of the “distress” signal, MICA, which can activate pathogenic MICA-NKG2D interactions and promote IFNg secretion by FFA-pathogenic CD8+ T cells. Linalool also increased the number of perifollicular CD68+ macrophages in healthy HFs ex vivo, while transcription of the chemokine, CXCL9, was increased in lesional compared to non-lesional FFA biopsies (RNAseq). When non-lesional FFA biopsies were exposed to linalool ex vivo, this also up-regulated bulge expression of MICA, significantly reduced the number of K15+ eHFSCs, and induced their co-expression of vimentin, indicating that linalool promotes pathological EMT in human eHFSCs. Thus, selected personal care product allergens can indeed promote core FFA pathobiology events and are thus best avoided.

ESDR382 - Environmental pathobiology of frontal fibrosing alopecia (FFA): Does linalool promote FFA development and progression by inducing epithelial hair follicle stem cell damage and MICA expression in the bulge?

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.