M2 Macrophage and Extracellular Matrix Genes Are Enriched in High-Activity Lichen Planopilaris

The study on 15 Caucasian patients with lichen planopilaris (LPP) examined gene expression changes following treatments with hydroxychloroquine (HCQ), narrow band ultraviolet B (NB-UVB), and low level laser light therapy (LLLLT). HCQ showed partial to full responses, while NB-UVB and LLLLT induced only partial responses. Gene expression analysis identified PTGER4 and DOCK2 as potential biomarkers of treatment responsiveness, with increased exhausted CD8+ T cells post-treatment. HCQ increased CYP1A2 and SSR2, NB-UVB increased SAA1 and decreased VEGFA, while LLLLT showed no significant gene changes. The study also found that M2 macrophage and extracellular matrix genes are enriched in high-activity LPP, with genes like CD68, COL5A1, and MMP9 upregulated in severe cases, suggesting roles in fibrosis and disease activity. NB-UVB and HCQ reduced fibrosis-related gene expressions, unlike LLLLT. The study suggests potential therapeutic targets and prognostic biomarkers, though larger studies are needed for validation.