Lichen Planopilaris Is Characterized By Immune Privilege Collapse Of The Hair Follicle's Epithelial Stem Cell Niche

The study investigated the pathogenesis of lichen planopilaris (LPP), a chronic inflammatory disease causing permanent hair loss, by analyzing scalp biopsies from 42 adult patients. It found that LPP is characterized by the collapse of immune privilege in the hair follicle's epithelial stem cell niche, known as the bulge. This collapse was evidenced by increased expression of MHC class I and II and a Th1-biased cytotoxic T cell response, alongside increased proliferation and apoptosis of epithelial hair follicle stem cells (eHFSCs). The findings suggested that interferon-γ (IFNγ) plays a significant role in this process, indicating that LPP may be an autoimmune disease. The study proposed that protecting or restoring immune privilege in the bulge could be a therapeutic strategy for managing this treatment-resistant form of cicatricial alopecia.